This is another contribution to the PolyPanels design competition.

It's a case / housing for Raspberry Pi 3 model B. (RasPi 2 will fit as well.)
It's based on the earlier entry "PolyPanel Raspberry Pi holder" at https://www.myminifactory.com/object/3d-print-92651

[Update 2019-09-01] Now there are also parts available for Raspberry Pi 4. Please choose accordingly: Part1 (bottom) / Part2 (front) / Part5 (right) -- I have tagged the STL file names so you know for which Pi type they're designed. [/Update]

RasPi boards are inserted and released in the bottom panel without tools, with the help of a meander in the base plate.
The hooks on top of the board holders and the grip bar on the moving holder need a little support, I couldn't do without it.

There are many many variations possible for each of the panels. For the beginning, I have made a closed top plate, one with cutouts for the CSI / DSI / GPIO cables, and a third version with only the GPIO cutout and mounting holes for a breadboard.
For the front panel I have uploaded variants with support hooks for HAT boards on the inside. The variants differ only in the distance between the Raspberry Pi board and the HAT board: 10 / 12.7 / 15 / 20 mm. These STL files need some support structures for 3D printing.

If your printer doesn't allow designs as large as 140 mm, you can try out the reduced size case which is based on a 2x2 PolyPanel square. The bottom PolyPanel frame had to be cut open for the moving part of the Pi holder hooks. The PolyPanel snaps have been removed at this place as well. There are STL files for small adapter panels to get the case back to its original size if you like.

There's also a complete set of panels and accessory parts to build a pan + tilt camera holder based on the top panel, controlled with two micro servos.
The swivel bearing needs some support for printing, therefore you can print two halves and glue them together.
You can insert 2 mm steel balls in the bearing holes, this will improve the smoothness of swivel movements.
Camera tilt operation will only work if you don't swivel further than 45 degrees left and right.

I have still some ideas, so in the coming days + weeks I plan to add more variants:

• cutouts for power switch and / or reset button
• cutouts + holding brackets for displays
• cutouts for connectors and displays of specific HAT boards
• cutouts for active cooling (air inlet for a small fan)
• anything you can imagine and even more

The design has been made in OpenSCAD. My first attempts using the PolyPanel design library by Jason Kronz have always generated STL errrors.
The current 3D files use imported PolyPanel snaps from https://www.myminifactory.com/object/3d-print-polypanels-snaps-only-89595

More versions of this Raspberry Pi holder design can be found on http://bastelstube.rocci.net/projects/MBS30_RasPi-Halter/RasPi-Halter.html

[Update 2019-08-30] Today I got printouts of the parts with UV-hardened transparent resin. Really cool! Watch the new photos! This allows you to use a HAT board with display and read the display contents through the closed top panel. [/Update]

[Update 2019-09-01] I have uploaded a few versions of the left panel with mounting holes for a cooling fan. Different fan diameters supported + different types of grids inserted into the air intake. Check the STL file names for info about fan properties. Please contact me if your favourite fan has different mechanical dimensions or if it shall be mounted in a different position. [/Update]