Short answer: To build an acrylic box, cut five or six panels with butt joints (front and back sit on the bottom, sides fit between them), sizing them with the measured sheet thickness rather than the nominal one, since 1/4 in. sheet is often about 0.236 in. Then weld one joint at a time against a square jig with water-thin cement such as Weld-On 4, which fixtures in about 3 minutes; give the box 24 hours before handling it hard.
Bonded box or tab-and-slot box?
There are two ways to build a box from flat acrylic:
- Bonded butt joints. Plain rectangular panels, solvent-welded edge to face. The cleanest look, used for display cases, risers, and storage boxes. Needs square, flat edges and some practice.
- Tab and slot. Interlocking fingers cut by laser, held by friction or a touch of cement. Easy to assemble and good for enclosures and kits, but the fingers show. See tab and slot design.
The rest of this page is about bonded boxes.
Key facts
- Joint: butt joints, edge to face, solvent-welded. Thin cement wicks about 1/4 in. into a tight joint (IPS).
- Edges: machined or routed, flat and square, not polished. Sheet makers warn that polished, flame-polished, or laser-cut edges carry stress and can craze under cement.
- Thickness: measure it. Nominal 1/4 in. cast sheet is commonly 6 mm (0.236 in.).
- Cure: Weld-On 4 fixtures in about 3 minutes and gives 65 to 80% of its strength in 24 hours; joints keep strengthening for weeks.
- Heat limit: Acrylite rates continuous service at 160 °F for extruded and 180 °F for cast sheet.
Which panel overlaps which?
Pick a layout and stick to it. The common one for an open-top box or a five-sided display cover:
- The bottom (or top, for a display cover) is the full outside length × width.
- The front and back are the full outside length, and sit on the bottom.
- The two sides fit between the front and back, also sitting on the bottom.
That way the long front face is one unbroken panel with no visible edge on it, and the side edges show only at the ends.
How do you work out the cut list?
For outside dimensions L × W × H and a measured sheet thickness t:
| Panel | Qty | Size |
|---|---|---|
| Bottom | 1 | L × W |
| Front and back | 2 | L × (H − t) |
| Sides | 2 | (W − 2t) × (H − t) |
Example: a 12 × 8 × 6 in. open box in "1/4 in." acrylic. Nominal 1/4 in. sheet is usually about 6 mm (0.236 in.), so measure yours. With t = 0.236 in.: bottom 12 × 8, front and back 12 × 5.764, sides 7.528 × 5.764. If you'd used 0.250 in., every joint would be off by 0.014 in. and the box would come out undersize or with gaps. More on this in acrylic's actual thickness.
For a closed box, add a top the same size as the bottom and subtract 2t from the height of the front, back, and sides.
How do you keep the box square?
Acrylic joints set fast, so you can't nudge a panel square afterward. Before you glue anything:
- Screw two straight boards or a pair of machinist squares to a flat base at exactly 90 degrees.
- Use a flat, smooth work surface (a piece of glass or melamine is good).
- Keep a few weights or blocks and some painter's tape handy to hold panels upright without clamping.
What order do you glue the panels in?
- Peel the film back from the joint areas only. Leave the rest on to protect the faces.
- Bottom plus front. Stand the front on the bottom against the jig. Run thin cement along the inside seam. Wait several minutes.
- Add one side against the front and the bottom. Cement the bottom seam and the vertical seam with the front.
- Add the second side the same way.
- Add the back last, cementing the bottom seam and both vertical seams.
- Let it cure for at least 24 hours before handling it hard or putting anything heavy inside. IPS says solvent joints keep gaining strength for several weeks.
If your edges are laser-cut, anneal the panels first (Acrylite: 180 °F for one hour per millimeter of thickness, then cool slowly for at least 2 hours) to lower the risk of crazing at the joints. Lay each seam horizontal when you apply cement so it wicks evenly. If you're struggling with bubbles, read bubble-free acrylic joints, and see how to glue acrylic for cement types and safety.
What are the options for lids and hinges?
- Lift-off lid: a top panel with a smaller "lip" panel cemented underneath that fits just inside the walls (about 1/32 in. clearance all round).
- Sliding lid: grooves routed in the side walls, or thin strips cemented inside to form a track.
- Hinged lid: small acrylic or metal hinges, cemented or screwed. Screws need holes drilled slightly oversize; tapped holes need 1/4 in. or thicker sheet.
- Magnetic catch: small rare-earth magnets set in drilled pockets and epoxied.
Does a display case need ventilation holes?
A sealed display case can trap humidity, which isn't great for some collectibles, and a case over electronics needs airflow. A few small holes (around 1/8 to 1/4 in.) in the back panel near the top and bottom, or a hidden gap under the base, let air move without looking like an afterthought. Cases holding warm items like lights need more airflow, since Acrylite rates continuous service at about 160 °F for extruded sheet and 180 °F for cast.
We build boxes too
We cut, edge-finish, and solvent-bond boxes and display cases. Send your dimensions and we'll handle the thickness math. See acrylic fabrication and display case ideas, or get an instant quote for cut panels to glue yourself.
Questions
What thickness acrylic should I use for a box?
1/8 in. works for small boxes up to about 6 in. on a side. 3/16 or 1/4 in. is better for display cases and boxes up to about 18 in., and larger cases often use 1/4 in. or thicker so the walls don't bow.
Can acrylic boxes have mitered corners?
Yes, but mitered acrylic joints are hard to bond cleanly and are weaker than butt joints. Most professional display cases use butt joints with polished edges.
Which edges should be polished?
Polish only the edges that show on the finished box. Leave bonding edges flat and unpolished; polished or flame-finished edges don't bond well.
Can a solvent-bonded acrylic box hold water?
A small, well-made box can, but solvent joints with bubbles or dry spots leak and weaken under constant water pressure. For tanks, use cast sheet, thicker panels, and two-part cement such as Weld-On 40 or 42, and size the walls properly; see acrylic aquarium thickness.
Which cement is best for an acrylic box?
Water-thin Weld-On 4 (or Weld-On 3 in dry weather) for tight, machined joints; Weld-On 16 only where the fit isn't perfect; two-part Weld-On 40 or 42 where you need gap-filling, outdoor durability, or maximum strength.