Two counts make the grid
- Dividers along X split the width. A count of n gives n + 1 columns.
- Dividers along Y split the depth. A count of m gives m + 1 rows.
- Compartments. (n + 1) × (m + 1), all of the same size.
- Compartment size. cell = (inner side − count × thickness) / (count + 1), once for the width and once for the depth.
Leave both counts at 0 for a plain tray. Set only one of them for a single row of compartments, such as a tray for pens.
Limits the form enforces
- Each count is a whole number from 0 to 20. A fraction such as 2.5 is refused.
- Each compartment must be at least as wide as the material is thick. If it would be narrower, the form says there are too many dividers in that direction.
The second rule is the one that bites in small trays. In 3 mm sheet with an inner width of 30 mm, four dividers along X give (30 − 4 × 3) / 5 = 3.6 mm, which is allowed. Five give (30 − 5 × 3) / 6 = 2.5 mm, which is under 3 mm and is refused.
Worked example: 12 compartments
Open tray, inner 180 × 120 × 50 mm, 3 mm sheet, two dividers along X and three along Y. The outer size is 186 × 126 × 53 mm.
| Direction | Dividers | Cells | Sum | Cell size |
|---|---|---|---|---|
| Width, 180 mm | 2 along X | 3 columns | (180 − 2 × 3) / 3 | 58 mm |
| Depth, 120 mm | 3 along Y | 4 rows | (120 − 3 × 3) / 4 | 27.75 mm |
That is 3 × 4 = 12 compartments of 58 × 27.75 mm, and ten parts to cut: a bottom, four walls and five dividers. The two dividers along X are as long as the inner depth, 120 mm, and the three along Y as long as the inner width, 180 mm. An automated script generates this same tray and checks its part sizes, and that the SVG and DXF hold one closed outline for each of the ten parts.
How the dividers go together
Dividers are loose panels as tall as the inner height. Where two cross, each gets a half-lap slot half the height deep, and they slide into each other. They are not jointed into the walls: the grid rests on the bottom between them. The drawer dividers page shows where the slots are placed, and the tray with compartments page how the parts are packed on a sheet.
Read this before you buy or cut
- Dimensions. You enter the inner width, depth and height. The outer size is the inner size plus two material thicknesses (an open tray has no lid panel, so its outer height is the inner height plus one thickness).
- Not test-cut. The geometry is computed and checked by a script (92 fixture assertions) but was never test-cut, so cut a test piece first and adjust kerf and material thickness.
- Made by AI agents. This tool and its code were generated by AI agents and no human maker has validated it.
- Price: $9 USD one-time.
- What the key unlocks: one licence key unlocks SVG and DXF download for any dimensions, in this browser tool.
- Refunds: Refund requests go through Gumroad, under Gumroad's refund policy.
- Free without a key. The form, the preview, the part list and the sheet size.