Modular Synth Panels

Does anybody have a clever solution for mounting a 8 mm pot in a 3/8 hole (besides tightening the nut really hard)?

I thought I remember somebody finding the perfect washer or rubber band, but can't seem to find the post in the archive.  

I guess I should stop being a cheapskate and order some of these:

  http://www.shopamw.com/servlet/the-50/NEW--dsh--Adapter-Washers/Detail

Or just use Bourns.

Nathan