Somewhere to keep the spare boards. Each bay is the seat out of the ESP32 case: the pins drop into blind trenches where nothing can bend them, the moulded header strips drop into the pocket that locates the board, and a spring tab at each end presses down on the board's edge so it stays put when the tray is tipped over. Two to six bays, printed flat, no supports.
| Material | PLA or PETG |
| Layer height | 0.2 mm |
| Walls | 3 |
| Infill | 15% |
| Supports | None |
| Orientation | As downloaded |
The spring tabs are 1.0 mm thick on purpose, so set the slicer to print them solid rather than leaving a hollow shell in the middle. Three walls does it.
If you have not printed the case, print its fit check frame first. It is the same seat, and it tells you in about twenty minutes whether your boards drop in.
The header pocket locates the board in both directions, exactly as in the case. What the case does with a lid, the tray does with four spring tabs, two at each end, standing in their own moats so they can bend.
They grip the ends and not the sides because the ends are the dimension worth trusting: across this pattern of board the length lands within about a third of a millimetre, the width wanders by nearly a whole one. A fixed lip cannot catch a spread like that.
Press a board straight down until both ends click. To take one back out, push up through the window in the floor of the bay, or pinch the board's edges in the scallops cut into the long walls.
| Outside | 58.8 x 94.3 mm |
| Height | 17.1 mm |
| Bay | 52.0 x 29.3 mm |
| Header rows | 25.4 mm apart |
| Header pocket | 0.2 mm a side |
| Under the pin tips | 1.0 mm |
| Tab preload | 0.3 mm |
| Tab over the board | 0.35 mm |
The walls clear the module by a millimetre, so a second tray sits flat on top of the first and closes it. Loading a board asks each tab for 0.65 mm of bend over 12 mm of blade, which is well inside what printed plastic will take again and again.