Prusa MK3/3s bed riser mod

Why I prefer this way.
- You can tighten down all screws separately, with the nuts takes ages as you need to tight each one in turn a small bit.
- It does no allow for any play on the side of the nylon nuts, if you tighten the nuts too much you can't tighten the screws, if you try it will be very hard or scratch the bed.
- Fixes the problem of any possible play between the screw and the base. As this keeps the screw under tension there will be no play.

Notes:
I print them with Flex45 but I guess any flexible filament will do like TPU. I guess silicone tubing as well but didn't tried.
I added a washer between the MK52 and the flex riser so that is not directly against the hot heatbed. I only had metal ones and still works fine.