I am looking to make a Fresnel lense mould (the width is 7mm)
The idea is I cut the blue into the top of metal and then push a plastic sheet over the top.
The other idea is to cut the blue into the side of metal and pull the sheet through the gap.
Is this a feasible idea.
I think your best bet would be making TWO molds, both the positive and negative with a required gap for the thickness of the sheet, and then making a ghetto surface plate to sand the top surface flat.
It would be a SIGNIFICANT investment in time and effort on your behalf though, especially given you can buy ones out of China for under $50
Probably easier to just go solar panel > induction heater.