Not sure if this would be a help. Though I haven’t been able to find cheap ptfe versions of those only expensive anodized aluminum ones which seem like they could be a lot cheaper.
… I know I throw this out there probably too much but you can always look into getting custom fabrication work done and shop around for the cheapest option for someone to make you rbf holders.
I can make a cad file to get it printed in whatever material. I use PETG for most stuff, it’ll tolerate at least 135f for long periods(highest I’ve tested long term)
I’ve got quite the collection of sizes they are awesome for many things. Clutch for holding round bottoms imo. I hope you are well brother @Concentrated_humbold
Misread silicone? I misread cork… and thought to myself well those probably wont do a very good job as replacement gaskets I wonder why he wants those for his lab…