BDR 3 cones

don't know the contour 3.3 screw-in thread metrics but here's what i do when i need something like this. take out one of the supplied screw-in feet. visit loew's or a similarly well-equipped hardware store. check in the nut bins 'til you find one that will fit your foot. then figure, by label or more trial-and error, the bolt that fits the nut. the bolt should be labeled by diameter (sae or metric) and thread count (per inch or cm). now you have the info to order your bdr screw-ins. maybe kinda tedious but it works. -kelly

Using Cornfed's advice, start with M6. I believe that is what it is, but it may also be M5. Good luck.

You could try using Blu-Tack instead( it is a type of hobbyists "clay" that is an easy to use temporary solution).

I have used it extensively - it also adds a bit of "dampening". It is reusable and easy to remove. Just
put a real thin layer between the base of your gear and the top of the BDR cone