I find that my K2 Plus tends to get a little too warm for PLA printing when I'm doing larger print jobs so I quickly designed this door prop to be printed in TPU. I find this does a great job of keeping the door open the proper amount to maintain a relatively low chamber temp (but not too low) while still keeping the door closed enough to be out of the way to prevent accidental damage. This is designed to be printed using 95a TPU with 1-2 walls (depends on your printer setup) to ensure that it's a soft surface for the door to rest against which should help prevent accidental damage from bumps to the door. 

I designed it to slot into the bottom right corner, however, if you wanted to use a couple of them to protect against door bumps during printing, you can always scale the model % down slightly to make it snug enough to grip further up the chassis.