Re: cardboard boat gauge panel
I planned on making it just how it is and maybe screwing it down to the exsiting glass. So I guess what I'm saying is that the mould you see is the part that will be attached to the boat. Does that make any sense?
Perfect sense
First it looks like your using Styrofoam board .. Yea..thats not going to work.
I stick with my first option .. lam a few layers of mat on waxed glass ( any flat glass ). Pop that off..cut your dash and dome out. Shape/fit your part as desired ( you can always bond some kind of ply on the back side of the dash..but the dome part is going to get a few more layers of glass later on after the part has been fitted ).
Remember that when building a part from the outside in you have to take into account of tolerances on the FIT side which changes every time you Add glass or any other material.
This is for making a one up Part only

.. not a mold or plug.
YD.