Replying to Wakeskating

kay i got a questions for all the newschooler wakeskaters, i have a cassette wakeskate, and i wanted to make a bi-level out of it, but i got 2 questions

1.how would i make a mold to make the top deck, like with the concave and rocker and all?
2.i was looking on my buds bi-level and it has a little metal square peiece in between to hold them togetger, like with the bolts from both ends going into it to hold them, i was wondering if just like a square peice of wood would work for that