Shoe rack - A1 Mini compatible

A shoe rack compatible with A1 mini.
It includes all necessary parts for mounting the rack, and a few different designs.

Parts description:
- Shelf: stackable shelf with spacers embedded.
- There is a “light” version: without the frame, to save filament.
- Spacers: additional spacers to increase space between two shelves.
- Spacers are 84 mm height.
- Shelf with its embedded spacers: suitable for very low shoes (I haven't tried though).
- Shelf + Pair of spacers: suitable for mid shoes.
- Shelf + 2 pairs of spacers: suitable for boots.
- Pins: to secure connection between each parts.
- 3 designs are available.

Optional parts:
- Tray: to put on top of the last shelf spacers, so that you can store small objects (keys, wallet…).
- 4 designs are available.
- Handle: to put with its spacers after the tray, so that you can move the rack.
- “Top with tray, without handle”: to put after the tray, if you don't want the handle.
- “Spa