Easy composites stock 2 part casting resin, simple room temperature cure. Available in small 1 liter quantities, 30, 60 and 90 shore A hardness.
Many 2 part PU's require oven curing and need quite accurate temperature regulation, just something to be weary of.

Maybe suitable just for testing purposes?

A little trick with moisture cure adhesive/sealant is to mix in a tad of hydroscopic filler (corn flour). Goes off in minutes rather than day's/weeks. This will affect its structural properties, but a possible solution.... If your a cheapskate like me! 😉