Little is known about the "Unofficial Aperture Science Human Relations And Comfort Group", but it seems to be a group focused on the well-being of human test subjects.
Digging in the archives have unveiled the thing I now share with you. "Waste Disposal Unit Accessory A", or for the humans amongst us, "Toilet Paper Roll Holder".
Perhaps there's more parts to be found?
You need the following vitamins:
4 x M3 nuts
6 x M3x10 bolts with countersunk heads
You also need a 3mm drill bit.
I haven't researched international standard sizing for toilet paper, but the files fit a 10cm wide roll, and you can change the size in the included source if needed.
Print "portal_rod_snap_test.stl" to make sure the geometry fits adequately. For easy reloading it should not be too tight.
Make any adjustments in the OpenSCAD file if needed. All source files are in "portal_tp_source.zip".
Print "portal_portal_2off.stl", one in blue, one in orange. I used what I had at hand, which was translucent blue PLA from Ultimachine, and orange "Amber Tint" PLA from Diamond Age Solutions. Having it transparent looks great, I'm especially pleased with the orange portal, while the blue could have benefited from being a bit stronger.
Print "portal_man.stl" and "portal_arm.stl" in black. Update: I split the parts in two files, as you might want to print the more detailed cube slower than the body.
Print the rest (L+R side, back and rod) in white.
Assemble as per the instruction pdf files.
Take a picture of your now upgraded bathroom and share it!