The polyester resin used for fiberglas is good, you don't actually need the fiberglas itself though it will make it stronger. But tupperware itself doesn't allow things to adhere well. Epoxy will work better than polyester or vinylester, but I don't think it's the answer. If you try it I suggest putting it on the inside rather than the outside.
What is determined to stick to ANYTHING? Urethane. Gorilla glue, for example.
But my real advice is to look beyond tupperware. I don't think you'll come up with anything that lasts.
You might try using the tupperware shape as a mold master to create a new casing. https://www.smooth-on.com/
A process similar to this would probably give you what you want. https://www.smooth-on.com/tutorials/2-p ... n-example/