Basis and table mats?

If you like the dental floss belt, try mylar tape, like VHS tape spliced to the correct loop length.

The Teres owners group have been down this road with the various belt types, and have tried the rubber, dental floss(silk cord), etc, and at present the 1/2" mylar tape is the best thing found.

You may have to try a different pulley, if your pulley has the V-groove in it for the round section belts. Tape requires a flat surfaced pulley, with flanges on top and bottom.

The main thing with tape belts and other non-stretch belts is that tensioning is more difficult, and is more critical.

Even slightly too loose, and the belt will fall right off the platter. Too tight, and the motor housing will start to tilt, and your pulley will not be vertical anymore.

It is a bit more fussy, but you do get better sound, if you are willing to take a little more time and effort in tensioning.

Simply a matter of less stretch and less slip.