Jadnashua
Retired Defense Industry Engineer xxx
You need to read the instructions. On a similar system, you do it in multiple layers...have not used that one. Also, last time I tried to find the materials, the shop handed me a tube they dug out of the back (hardly ever used it) that was 10-years past its 'use by' date...hopefully, the stuff you get is still good. The donuts are much more common in use as, if you get the right size, it's much quicker and cleaner. If that doesn't work, the next most common way to do it is with a hubless connector, but depending on the situation, that might require cutting more out (or not)!