Assembly Guide
Build it right
the first time.
Most painting problems start at assembly. Mold lines left on, parts glued in the wrong order, gaps that won't close. This guide covers what the official instructions skip — so your models are ready to paint, not fighting you.
What you need
Four tools. That's genuinely all you need to build almost any plastic kit Games Workshop produces.
Sprue cutters (clippers)
~$10–20The most important tool. Thin-bladed flush cutters are the best — they leave smaller nubs and cause less stress damage to parts. Don't use scissors. Don't use your teeth.
Hobby knife (X-Acto #1 or similar)
~$8–15For trimming mold lines, scraping gates, and cleaning up parts. Keep it sharp — a dull blade tears instead of cuts. Replace blades often, they go dull fast.
Plastic cement (Tamiya or GW)
~$8–12For plastic-to-plastic joins. Chemically melts the plastic and creates a bond stronger than the plastic itself. Slower than superglue but the right tool for plastic kits.
Superglue (thin or medium viscosity)
~$5–8For resin parts, metal bits, trophies, basing materials, and anything that isn't plastic-to-plastic. Loctite or Gorilla Glue work fine — GW brand is the same thing at twice the price.
Fine files or sandpaper (400–600 grit)
~$5Optional but useful for smoothing stubborn mold lines and cleaning up glue joins. A set of hobby files covers everything.
Blu-Tack or modeling putty
~$4For holding parts in position while glue dries. Invaluable for awkward joins and for dry-fitting before committing.
Plastic cement vs. superglue — use the right one
Use plastic cement when:
- → Gluing plastic to plastic
- → Both parts are from the same kit
- → You want the strongest possible bond
- → You have time to hold the join
Use superglue when:
- → Gluing resin or metal parts
- → Attaching small detail bits
- → Fixing broken parts
- → Basing materials and tufts
Which sprue cutters should you buy?
Clippers matter more than most new hobbyists expect. Cheap wire cutters from the hardware store crush plastic as they cut, leaving white stress marks and torn parts. A proper flush cutter makes a clean cut. Here are the ones worth buying.
IGAN-330 Flush Cutters
The best budget cutter on Amazon. Sharp blade, clean flush cut, comfortable spring action. Not as refined as the Tamiya or DSPIAE but 90% as effective at a third of the price. Solid first pair — upgrade later if you want.
See price on Amazon →DSPIAE AT-A Single Blade Nipper
The most purchased hobby nipper on Amazon by a wide margin — and for good reason. Single-blade design means only one side of the blade contacts the part, eliminating the compression mark that twin-blade cutters leave. Noticeably cleaner cuts than standard flush cutters. The step up that makes a real difference.
See on Amazon →Tamiya 74123 Sharp Pointed Side Cutter
The cutter recommended by painters and YouTubers for over a decade. Sharp, precise, excellent build quality. The pointed tip gets into tight spaces other cutters can't reach. Not single-blade like the DSPIAE, but extremely refined for the price.
See on Amazon →GodHand SPN-120 Sprue Nipper
Japanese-made, single-blade, razor-sharp. The cutter serious hobbyists eventually buy and then never replace. Leaves virtually zero gate mark on the part. Overkill for beginners but genuinely worth it if you're going to build a lot of models. Treat the blade carefully — they can chip if used on metal or resin.
See on Amazon →The honest buying guide
Start with the IGAN-330 or DSPIAE. Most beginners end up buying the DSPIAE after one upgrade — skip the middle step if you can. The GodHand is genuinely excellent but not necessary until you know you'll be in this hobby long-term. Whatever you buy: don't use it on metal, wire, or resin — single-blade nippers especially will chip. Plastic only.
Which hobby knife should you buy?
The hobby knife is your most-used tool after cutters. It scrapes mold lines, cleans gates, and trims flash. You want a comfortable handle and a blade that's genuinely sharp — a dull blade drags and tears instead of cutting cleanly. Replace blades often; they go dull faster than most people expect.
X-Acto #1 Knife with #11 Blades
The standard hobby knife for decades — sold at every craft store and on Amazon, with replacement blades everywhere. The #11 blade is the go-to for miniature work: fine point, great for scraping mold lines and trimming gates. Not the sharpest knife on this list but the most accessible. Start here.
See price on Amazon →Swann-Morton No. 3 Handle + 10A Blades
Surgical-grade blades made in Sheffield, UK. Noticeably sharper than X-Acto straight out of the pack — the difference is real and immediate. The No. 3 handle is slim and precise, preferred by a lot of competitive painters once they try it. Fits #10A blades (the standard hobby choice) as well as #10, 11, 12, and others. Easy to find on Amazon. The blade that makes scraping mold lines feel effortless.
See on Amazon →X-Acto X3000 Rubber-Barrel Knife
The X-Acto with the textured rubber grip — noticeably more comfortable than the standard aluminum handle during long assembly sessions. Same #11 blades, same brand, just a better handle for extended use. If you know you'll be building a lot of models, start here instead of the plain #1.
See on Amazon →Blade discipline
Replace blades more often than you think you need to. A dull blade requires more pressure — and more pressure means more control loss and more gouging. If your knife feels like it's dragging rather than cutting, change the blade. A pack of 100 replacement #11 blades costs about $10 and lasts years. Always cap or retract the blade when setting the knife down. Always cut away from your fingers. Always.
Which plastic cement should you buy?
Plastic cement works by chemically dissolving both surfaces and fusing them into one piece — stronger than the plastic itself. It's not an adhesive in the traditional sense; it's a solvent weld. This means it only works on plastic (not resin or metal), and it only works if both surfaces are smooth and flush. The right cement makes a huge difference in how confident your builds feel.
Tamiya Extra Thin Cement (87038)
The one almost every experienced hobbyist uses. The brush applicator draws cement into a join by capillary action — you touch it to the seam and it flows in on its own. That means you apply it after dry-fitting, not before, and you get a clean join every time with minimal squeeze-out. Sets in 1–3 minutes to working strength, full cure in a few hours. The green-lidded bottle.
See price on Amazon →Tamiya Extra Thin Quick Setting (87182)
Same capillary formula as the 87038 but with a faster catalyst — working strength in 30–60 seconds instead of minutes. Useful when you have a lot of identical pieces to assemble (infantry squads, terrain) and don't want to hold each join for long. Slightly less forgiving for repositioning. The orange-lidded bottle. Buy the standard first; add this one once you know your workflow.
See on Amazon →Revell Contacta Professional
A thicker cement with a fine metal needle applicator — useful when you need to place glue precisely on a small contact point rather than wick it in from outside. Popular for small multi-part joins where the Tamiya brush applies too much. Slightly slower to cure than Tamiya Extra Thin. A solid second bottle to have alongside the Tamiya.
See on Amazon →What about Games Workshop plastic glue?
It works fine — it's in every GW store and you'll see it recommended constantly. But it's a thicker, slower cement with a brush applicator that's harder to control. You pay more for less product. If it's what you have, use it. If you're buying from scratch, get the Tamiya instead — it's cheaper, better to apply, and available everywhere.
Understanding the sprue
Your models arrive attached to plastic frames called sprues — the rectangular grids of plastic that everything is cast onto. Parts are connected to the sprue at specific points called gates. The job is to remove parts cleanly without damaging them.
Every part on the sprue is labeled with a letter and number combination that matches the instruction booklet. Before you clip anything, read the instructions and understand which parts belong to which step. GW instructions show parts by their code — find the part on the sprue before you cut.
Don't clip everything off at once
New builders often clip all the parts off the sprue before starting, then lose track of which part is which. Instead, follow the instructions step by step — clip only the parts you need for the current step, assemble them, then move to the next step. The sprue is your parts organizer. Use it.
The assembly process
Every model, every kit, every faction. This is the order.
Read the instructions first
The whole thing. Before you touch the sprue. GW instructions are visual and mostly straightforward, but there are sub-assemblies and ordering constraints you need to know before you start gluing.
Clip with two cuts — never one
Cut #1: clip away from the part, leaving a 2–3mm nub attached to it. Cut #2: clip the nub as close to the part as you can. This two-step approach prevents stress marks and pulled plastic that can ruin a surface.
⚠ One cut right at the gate often pulls a chunk out of the model. Always leave a nub first.
Remove mold lines
Hold the part up to a light and rotate it. You'll see a thin raised line running across the model — this is the mold line, left over from where the two halves of the mold meet during casting. Every part has one. If you paint over it, it looks terrible.
How to remove mold lines
Hold your hobby knife perpendicular (90 degrees) to the mold line and draw it along the line with light pressure — you're scraping, not cutting. The raised plastic shaves off cleanly. For curved surfaces, a round file or fine sandpaper works better.
⚠ Don't use the blade edge-on to slice along the line. You'll gouge the model. Scrape, don't slice.
Dry fit everything before gluing
Hold all the parts together — no glue — to check they align correctly. Most kits fit well, but some joins need slight pressure or a specific order. Identify any problems now, before they're permanent.
Decide on sub-assemblies
Some areas are impossible to paint after assembly. Decide which parts to leave off until after painting. Common sub-assemblies: arms/backpack on Space Marines, head on Guard infantry, separate weapons. More on this below.
Apply plastic cement to one surface only
Apply a thin layer of plastic cement to one part of the join. Wait 10–15 seconds for it to begin activating the plastic surface, then press the parts firmly together and hold for 30–60 seconds. The cement melts both surfaces, creating a chemical weld.
⚠ Too much cement causes plastic to swell and squeeze out of the join. A thin coat is better than a thick one.
Check alignment before the glue sets
You have a short window — 15–30 seconds with plastic cement — to adjust position. Check the join from multiple angles, particularly the front. Twisted torsos and canted heads are permanent once the glue cures.
Let everything cure before painting
Plastic cement reaches working strength in minutes but full cure in 24 hours. For best results, build your models the night before a painting session. A partially cured join can snap under spray primer pressure.
Sub-assemblies — the technique most guides skip
A sub-assembly is leaving a part off until after painting, so you can reach areas that would be blocked by it.
Consider a Space Marine: if you glue the arms on before painting, you can't reach the chest aquila or the torso details between the arms. But if you leave the arms off, paint the torso fully, then glue the arms on after — everything is accessible, nothing is masked, and the result looks much cleaner.
You don't need to do this for every model — basic Guardsmen or Poxwalkers don't need it. But for complex multi-part characters and anything with an arm that covers the chest, sub-assemblies save significant frustration.
Good candidates for sub-assembly
- → Arms on Space Marines and CSM
- → Heads on any infantry model
- → Backpacks on Space Marines
- → Weapon arms on large monsters
- → Capes and cloaks on characters
- → Separate torso/legs on multi-piece infantry
What to use instead of glue temporarily
- → Blu-Tack to hold parts while painting
- → Small pieces of cork or foam as handles
- → Cocktail sticks stuck into the part's connector
- → Alligator clips for very small parts
Mistakes that ruin models before you paint them
✗ Clipping right at the gate in one cut
Always two cuts. The first cut leaves a nub. The second removes the nub. One cut at the gate stresses the plastic and often tears a chunk out — especially on thin details like sword blades and antennae.
✗ Skipping mold line removal
Mold lines are invisible until you paint them, then they're all you can see. Five minutes per model with a hobby knife before assembly saves you from a model that looks unfinished no matter how well it's painted.
✗ Too much glue
Plastic cement: one thin coat on one surface, that's all. Superglue: a tiny dot per join. Excess glue squeezes out of joins, fills in surface detail, and is nearly impossible to remove cleanly.
✗ Not dry-fitting before gluing
Some parts only fit one specific way, and it's not always obvious which way. Dry-fitting reveals alignment issues, backwards parts, and wrong-part-in-wrong-slot errors before they become permanent.
✗ Gluing parts in the wrong order
Instructions exist for a reason — some parts block access to others if assembled in the wrong sequence. Torso before legs. Main body before arms. Read the whole instruction sheet once before starting.
✗ Priming immediately after gluing
Plastic cement needs at least a few hours to reach real strength. Spray primer at pressure can break a fresh join. Build the night before, prime in the morning.
✗ Using the wrong glue for the material
Plastic cement only works on plastic. On resin or metal, it does absolutely nothing. Those need superglue. Most kits are plastic, but some special characters and older kits are resin — check before you glue.
How to fix common accidents
? Part broke off the sprue and left a chunk missing
If the chunk is still on the sprue, glue it back carefully. If it's gone, fill the gap with Green Stuff (a two-part modeling putty), let it cure, then smooth and sand. Small imperfections can also be hidden with basing material or painted as battle damage.
? Parts glued slightly out of alignment
If caught immediately (within 30 seconds of plastic cement): twist firmly to break and reset. If fully cured: carefully score the join with a knife, use isopropyl alcohol to soften, and try to twist apart. Expect some damage. For minor misalignment, sometimes it's better to leave it and adjust your painting to draw the eye elsewhere.
? Superglue on fingers (bonded skin)
Don't panic. Don't pull. Soak in warm water for a few minutes to loosen, or use nail polish remover (acetone) carefully. Acetone also dissolves superglue from model surfaces if you need to unstick a join.
? Visible gap between parts
Small gaps: liquid plastic cement wicked into the gap can partially fill it. Medium gaps: Green Stuff or Vallejo Plastic Putty, sanded smooth when dry. Large gaps: usually a sign the parts weren't aligned correctly — consider rebreaking and regluing.
? Mold line discovered after priming
Carefully scrape with a hobby knife. The primer will come off but that's fine — it'll be covered by paint. Sand lightly if needed. Re-prime the area with a touch from a spray or brush-on primer.
Ready to prime and paint
Before you prime, do a final check:
Priming tip
Spray from 25–30cm (10–12 inches) away in short, sweeping passes. Rotate the model between passes to catch every angle. Multiple thin coats beat one thick coat — thick primer fills in fine detail and looks rough. Don't prime in cold weather (under 10°C/50°F) or high humidity — the paint will granulate. When in doubt, prime indoors.
Built. Now paint it.
Assembly done right means painting goes smoothly. No mold lines emerging halfway through, no parts falling off mid-session. Take your time here — it pays off.