Building 1 time use mold. input?

[abl1111]

Bingo !!! With all the input form you guys, I have it in my mind what needs to be done to make the mold. Thx all around !!!

Last question(s):

When installing a 3/4" plywood "top" ( the part where the pedestal seat will mount), at what point do I install this prefitted pc ?

Does this sound right ? Gelcoat should be semi-cured. Wet out and laminate the entire inside of the box, then place the wood on the top ( weighted down w/ something to make a nice bond )? After cured, sand top area and w/ wetout mat, sandwich the wood?

Thx,

Alan