Its probably not news to MM3 owners that the stock motor plates (especially the Z motor plates) are a bit thin. I have known this issue since day 1 of assembling my MM3 so the first thing I did was attempt to support them. Unfortunately this had not helped much.
Bent Plate
(as you can see in this pic)

This has caused me all sorts of bed leveling woes. I heard that there where some 3rd party thicker plates available so i thought heck ill try them out. has all of the motor plates for each axis and are also good for other projects you may be working on
The new plates are made from stainless steel and are much more ridged than the stock ones
Bent Plate Bent Plate

They also have an extra mounting hole that I found nice as my stock plate had buckled a bit in the center
Bent Plate

After installing I noticed a big difference in the rigidity and was able to level my bed. I don't think these plates will be bending anytime soon so my bed should stay level. YAY!!!!!
For the price I feel that this is a well worth it upgrade for my bot.