Quick answer: judge an acrylic case on measuring, sheet thickness, UV protection, joint type, sealing and base flatness, and only then on price. If any one of those six fails, a cheaper case is not a bargain. Anything above roughly 2500 pieces should be measured and made to fit, because universal boxes will not hold it. If you still need to size a box by piece count, start with our display case sizing guide; this article is about how the case itself is built.
1. Measure the model, not the box
The number one failure with acrylic cases is buying one that is too small. Set boxes list a piece count, not finished dimensions, and manuals rarely include them. Build first, then measure with a tape: length, width and height at the most protruding points, then add two to three centimetres of clearance on each axis.
That clearance is not wasted space. You need room for your fingers when lowering the model in, acrylic panels have cutting tolerances, and spare headroom lets you add an LED strip later. Three spots get forgotten: antennas and gun barrels push height up by several centimetres; a base with a name plaque adds width; and modular buildings placed side by side need extra room at the joint.
2. Sheet thickness: 2 mm is the floor, 3 mm is standard
The stiffness of acrylic in bending scales roughly with the cube of thickness, so 3 mm is not half again as rigid as 2 mm, it is closer to three times. In practice, 2 mm only makes sense up to about 30 cm; by 40 to 50 cm the long sides visibly bow and the lid sags in the middle. 3 mm is the usual spec for custom cases. Past 60 cm on the long side, or when the top panel carries load or another case, go to 5 mm and ask for a stiffening edge.
The field test takes a second: press the middle of a long side with one finger. It should spring back with almost no visible deflection. If it feels soft or the dent stays, the sheet is thin or low grade. Check the cut edges too — laser-cut acrylic should look clean and bright. A milky, burnt or rough edge means it was never polished, and rough edges are where hairline cracks start.
3. Clarity and grade: regrind turns blue-grey
Virgin acrylic is highly transparent with a clean, bright cut. Sheet made with regrind or filler looks identical from a distance and obvious up close: hold it against white paper and the face goes blue or grey, with specks and bubbles along the edge. Stack two sheets and the difference is clearer still — good material just darkens slightly, regrind goes cloudy.
New cases ship with protective film on both faces. Leave it on until assembly is finished and the fit is confirmed. Peel it early and a grain of grit on the table becomes a scratch that you will never polish out.
4. UV: transparent is not the same as UV blocking
Plain clear acrylic blocks very little ultraviolet light, whatever it looks like. White, light grey and tan parts placed near a window yellow within about a year, and the change is permanent. Sheet with a UV coating or UV additive is normally sold with a blocking figure, and the marketing numbers usually claim ninety percent or more. If no figure is quoted, assume no UV protection and keep the case out of direct sun.
If the display spot cannot move, add a blind, apply window film, or turn the case so the back faces the window. Dust and light are separate problems; the dust side is covered in our dust protection notes.
5. Joints: clips, screws or glue — the difference is whether it comes apart
There are three common constructions. Clip or connector-block cases snap the panels together: fast to assemble, visually clean, and they come apart again, though the connectors are consumables and loosen with repeated disassembly. Through-bolt cases use screws and nuts from the outside: the most rigid option, but the fixings are visible unless the maker supplies cover caps. Glued cases are the cheapest and the worst to live with: they cannot be taken apart, glue squeeze-out is hard to remove, and solvent stress leaves white crazing.
Before buying, ask two questions: are spare connectors included, and does the manual show the assembly order. A seller who can answer both usually trusts their own structure.
6. Sealing: a grooved base, a stepped lid, a magnetic door
Dust gets in through gaps. Well-made cases cut a groove in the base so the side panels sit inside it rather than standing on a flat sheet; the lid sits in a step above the sides; a front door closes on magnets or clips instead of resting by gravity.
The practical test is simple: with the model out, shine a torch from inside and look for light leaking through the seams. Under about a millimetre of gap blocks most settling dust, but no acrylic case is airtight, so in humid rooms put a small silica pack inside and swap it every few months.
7. Base and stacking: flatness decides whether the model rocks
A warped base makes a perfectly built model look badly built. Set the case on a flat bench and press the four corners; a click means the base is twisted or the joints are not fully seated. Rubber feet help, since hard acrylic will mark a wooden desk.
Stacking needs three conditions: same footprint, same sheet thickness, and support under the lowest unit. Plastic creeps under sustained load, so two layers are usually fine, but from three up, add a board or metal posts between cases or the bottom lid will slowly dish.
8. Cleaning: keep alcohol away
Acrylic dislikes alcohols, ketones and ammonia. Wiping with alcohol, glass cleaner or ammonia-based spray causes clouding or crazing, and neither can be reversed. Use a microfibre cloth with dilute neutral dish soap, wipe wet, then finish with a dry microfibre. Never scrub dry, and skip paper towels — the fibres and grit leave fine scratches. For static dust on the inside, a treated anti-static cloth or a very dilute neutral wipe left to air-dry works; do not use a hot hairdryer, because heat distorts the panels.
Piece counts from our own library
| Build size | Pieces | Starting internal size | Example from our database |
|---|---|---|---|
| Small to mid | around 900 | 35 x 25 x 25 cm | Large Pikachu (911 pieces) |
| Large | around 1600 | 55 x 35 x 35 cm | Fujian carrier (1621 pieces) |
| Very large | 2900 and up | measure and build to fit | Pirate ship (2912 pieces), Koenigsegg hypercar (4104 pieces) |
Piece count is only a rough filter. Dense one-piece builds, and anything with masts or rigging, take up far more height than the number suggests. The internal sizes above are starting points derived from comparable sets in our library — before ordering, go back to step one and measure your own model.
When acrylic is the wrong answer
Two cases. If you take the model down and handle it often, lifting a whole acrylic cover every time gets old; a glass-door cabinet is friendlier. And past about 60 cm on the long side, custom acrylic is priced by area, so the same budget often buys a ready-made cabinet with glass doors that also solves dust and lighting in one go.
FAQ
Will acrylic yellow? Virgin sheet with a UV coating, kept out of direct sun, lasts many years. Uncoated sheet in a bright window can show a colour shift within a year or two, and it cannot be cleaned off.
Can I add lighting inside? Yes. LED strip runs cool enough not to affect bricks. Route the cable through the base groove rather than pinching it in a side seam, or you break the seal you paid for.
Why does the inside attract dust? Static. Wipe with an anti-static cloth, or with very dilute neutral cleaner and let it air-dry. Do not rub with a dry cloth.
Can I wash it with water? The panels can, but connectors and magnets should not be soaked. Remove the cover, rinse it alone, dry fully, then refit.
Is a used case worth buying? Only check two things: scratches on the panels, and whether all connectors are present. Missing clips are nearly impossible to replace unless the seller can identify the spec.