Raspberry Pi 4 model B OpenScad model w/IO

While looking at [Octo duct](https://www.thingiverse.com/thing:3329293) I realized I wanted one for my RPi4, but noticed the IO ports were in the wrong places. Then I looked around for an RPi4 OpenSCAD case model to adapt and found [Raspberry Pi4 Sheath Case (SCAD)](https://www.thingiverse.com/thing:3728620). Then I found [Raspberry Pi 4 model B OpenScad model
](https://www.thingiverse.com/thing:4712611) and realized I could add some features to provide clearance for the IO connections, and use that to carve an RPi4-shaped space out of anything else.

Please find attached a remixed OpenSCAD file with added IO clearance features, and a couple STLs, including a block and a sphere with a Raspberry Pi 4-shaped hole differenced out of them.

For example, the skull-rpi4.jpg file was created in PrusaSlicer by plating the Low Poly Skull https://www.thingiverse.com/thing:906562 and Plater/Right-click/Add Negative Volume/Load RPi4board_shaped_hole.stl and then juggling around with the sc