I just use the exhaust fan for temperature control.

I made a sleeve of aluminum foil bubble insulation for mine. I taped it together with aluminum HVAC tape. It makes the enclosure heat up quicker, but I have to run the enclosure fan on longer prints to keep it from getting too hot.

You must live somewhere dry. I have to keep my filament in a box with silica gel.

They could be made fairly small. The Curta calculator was hand held. Unfortunately, they are very expensive now, but there is a simulator online if you want to play with one.

The printing services are good if you need metal prints or if you need resin prints and can’t deal with the fumes and mess.

If you just need filament prints, it’s better to buy a printer. It really sucks to wait a week or more for the part to show up only to find that you made a mistake and it doesn’t fit.

One of those cheap Chinese mini PCs with an Intel N100 will give very good performance while drawing about 5 watts at idle.

You can print a playable record on a high end resin printer, but the audio quality is very bad. It would be impossible on an FDM printer.

I would through bolt the TPU and use a large washer on each side. Teflon lubricates the threads making it easier to turn. You want thread locker to keep a bolt from coming loose. Be careful with the thread locker since it eats many types of plastic.

All you should have to do is open the port in your firewall to the server. Also, make sure you are allowing ICMP through the firewall. It’s important for IPv6 and shouldn’t be blocked. If your server is running a firewall, don’t forget to open the port there too.

To test if it’s working, you can use the 5G connection on your phone since it should have IPv6.

If the scanner was working fine with the Pi before, I would suspect the USB cable or power supply. Try a different power supply and cables. The Raspberry Pi 3B+ can supply 1.2 amps from its USB ports which is sufficient for 2 bus powered devices. A powered USB hub can be used if you need to connect more bus powered devices to the Pi.