(Copy/paste from my post on the other site)
Here's what I did.
Go here to download the file for free: https://www.thingiverse.com/thing:1775953
Then go here to upload the file and have the riser printed: https://www.makexyz.com/
Specify the following on the makexyz website:
Color: Green (or whatever color you want)
Infill: 50% (the default is a lower % which may not be strong enough)
Layer height: 0.2mm
Then wait for it to arrive. This was my first foray into 3D printing and it was very easy and inexpensive. The two websites listed above are very intuitive to use, no expertise required.
For installation, I used stainless M6 x 40mm hex-head bolts and M6 flat washers (you can also use flange-head bolts, which would eliminate the need for the washers.) I think 40mm is the minimum bolt length you can get away with; others have used 45mm or 50mm. Took less than five minutes to swap out the risers.