The seymo stuff is fairly hard and not rubbery
Mike might have some kicking about , you could borrow one
It's only a tiny amount you need. Heating the foot only should give spot on results.
The wee cups should come with the kit
unless you are using something different.
Cough medicine cups are ideal
and reusable once the epoxy goes hard and can be popped out.
Lots of good flytying/rod building friends can be found at the chemists.
Sandy