Cleaning Candle Wax Residue off Candle Wax Disc Saver?

I have some heavy weight plastic discs that are used to keep the wax from dripping down on your table from your lit candles, but the disc eventually needs to be cleaned. Other than scrapping the wax off (the plastic is heavy, but rather soft) what other suggestions would someone have to clean these?

Thank you.

By Shirley Ann S.