The double-sided carpet tape at Ace Hardware stores seems to work well, to hold work.
Steps:
Turn and set up the waste block face plate.
Screw the faceplate onto the jig faceplate
Assemble the rest of the jig, centering and zeroing the faceplate.
Turn the faceplete round and flat n the outer face surface
Put 2-sided tape (or hot glue) on the faceplate, and stick your medallion (or other piece) to it.
Use the spreadsheet to determine how to configure the jig, make the cuts.
I recommend that if you experiment and find a pattern that works well – record that pattern in the spreadsheet format and safe it.
This allow you to repeat it in the future.