If you want to print with anything other than PLA, you need your printer bed to stay warm. For the MP Select Mini, that means some kind of enclosure to keep the ambient air out.
I found this excellent tutorial for creating an enclosure. Luckily, it is designed in a way that will not cause overheating for the electrical components:
But it is missing something to keep the box from falling over. The author suggests creating an additional support with extra poster board. I have done this, but my version just wasn't quite as elegant as I would like.
This 3d printed version does the trick. It screws into the same holes that are already present. Very sturdy.
I also used the re-routed the MP Mini board upgrades available here.
https://www.thingiverse.com/thing:1712796 (just the split part 1)