One of the most common questions when starting with laser cut boxes is: what thickness should I use for this box? The answer depends on the box size, what it will hold, and the material you're cutting. This guide gives you practical rules and a reference table to make that decision quickly.
Material thickness affects three things:
Using 3mm MDF for a large box that will hold heavy tools is a recipe for failure. Using 6mm plywood for a small jewelry box makes it unnecessarily heavy and the joints harder to assemble precisely.
A good starting point: box internal dimension ÷ 15 = minimum material thickness in mm.
So a box that's 300mm wide should use at least 20mm thick material — that's structural lumber territory. For laser cutting, the practical limit is usually 6mm, which means you need to think about internal supports or bracing for very large boxes.
For decorative or light-duty boxes, you can be more lenient:
| Box longest dimension | Recommended thickness | Suitable for |
|---|---|---|
| Up to 100mm | 3mm | Jewelry, small gifts, trinkets |
| 100–200mm | 3mm–4mm | Medium gift boxes, organizers |
| 200–350mm | 4mm–6mm | Storage boxes, tool trays |
| 350mm+ | 6mm+ | Large storage, requires bracing |
Finger joint width should be roughly 1.5× to 2× the material thickness. This gives joints that are strong enough to hold together while being small enough to look clean.
| Material thickness | Recommended finger size |
|---|---|
| 3mm | 4–6mm |
| 4mm | 6–8mm |
| 6mm | 8–12mm |
In Box Studio, you can set the finger size directly. If you're unsure, leaving it at the default (auto-calculated based on thickness) is a safe choice for most projects.
A finger joint is only as strong as the glue surface or friction contact it creates. Larger fingers mean more surface area per joint, which translates to a stronger connection. However, very large fingers on thin material can cause the panel edge to look disproportionate and the joints to feel chunky.
The 1.5–2× rule balances aesthetics and strength. For boxes that will hold heavy items, lean toward 2×. For decorative boxes where appearance matters, 1.5× gives cleaner-looking joints.
Here are some practical sizes for common projects, ready to plug into Box Studio:
Small jewelry / ring box - External: 80 × 60 × 40mm — Material: 3mm MDF or plywood
Playing card box (standard deck) - External: 95 × 70 × 25mm — Material: 3mm
Pen / pencil box - External: 200 × 80 × 45mm — Material: 3mm
A4 document box - External: 220 × 310 × 60mm — Material: 4–6mm
Keepsake / memory box - External: 250 × 180 × 120mm — Material: 6mm plywood
Tool storage tray - External: 350 × 250 × 80mm — Material: 6mm, consider corner bracing
Arduino / Raspberry Pi enclosure - Depends on board size + clearance for ports and cables — measure your board and add 5–8mm on each side
Box Studio works with internal dimensions — the usable space inside the box. The actual external size will be larger by 2× the material thickness on each axis.
So if you need a box to fit a 90mm × 60mm object: - Set internal dimensions to 92 × 62mm (2mm clearance) - With 3mm material, external size = 98 × 68mm
Always measure what the box needs to hold before entering dimensions.
The right amount of clearance depends on what the box holds and how tight you want the fit:
For objects with cables or connectors, remember to account for those too — a box that fits the device perfectly but doesn't let you plug in the charger is frustrating.
| Load type | Recommendation |
|---|---|
| Paper, fabric, light objects | 3mm MDF |
| Electronics, books, moderate items | 3mm–4mm plywood |
| Tools, bottles, heavy items | 6mm plywood |
| Very heavy loads | 6mm + internal supports |
MDF is heavier than plywood at the same thickness, so for large boxes you'll often want plywood both for weight and strength.
Never trust the nominal thickness. A sheet sold as "3mm MDF" might actually be 2.8mm or 3.1mm. This small difference matters enormously for finger joints — if you enter 3mm but cut 2.8mm material, your joints will be slightly loose.
Always measure your actual sheet with digital calipers before entering the thickness in Box Studio. Measure in several places across the sheet — thickness can vary slightly from one area to another, especially with lower-quality material.
Box Studio handles all the joint geometry automatically once you set your dimensions, thickness, and kerf. Plug in your numbers and download a clean SVG ready to cut.
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