[Dragonfly DIY] Updates to Monoprice MP Select Mini printer

A couple of months ago I bought the $200 Monoprice mini 3D printer. I really like it. It has some warts but in general it's nice, small, portable, and just does the job.

Things I wouldn't mind seeing improved:

Temp control isn't as good as it was in my PID tuned RepRap. They may be using bang-bang not PID.
Arm stability is just a little wobbly.
The Z axis endstop could really stand to be adjustable, for trying different print surfaces.
The hotend is fragile

The Z axis switch is just fixed in place. When I decided I wanted to put glass on top of the print surface, the surface couldn't be cranked down far enough so I had to bend the arm on the switch. I will try to come up with a better solution to this later.

The hotend works well at first, but as soon as I had the first trouble with it, it became very cranky and started causing a lot of trouble, The 30mm fan failed which led to a bunch of jamming because I was too dense to notice the fan not running. Once the fan was replaced I still had issues, and the little springs like to go flying around the room when you disassemble it.

I had already ordered a new hotend to go with it. I decided to try out one of the $10 E3D all metal clones out of China. When it came in, I was very impressed with the quality. I actually owned a legit E3D a while back, and I don't think I could really tell the difference.

In any case, I used the hotend adapter that Benchoff posted on Hackaday and Thingiverse.

It works very well, and I got a bag of 0.4 and 0.5mm nozzles to play with.

I have some PETG filament coming which prints at 235 degrees, so the all metal hotend