Uni-Mould What I did wrong?

I am making cf wrist protections for roller or snowboard.

I decided to make a print of my hands with plaster bands (ones used in hospitals to repair broken bones).

Then I reinforced them with EC Pattern Coat Primer and Hi Gloss (also some car body filler)

It was my first attempt to use those products and it was great to do it.

Then I used those glossy hand prints to make a mould with EC Uni-Mould.

Maybe here is where I made a mistake - do not know

I made a positive mould from the imprints and it released perfectly.

Then I made a negative mould of the uni-mould mould.

I used 5 coats of easy lease release agent and a coat of wax. I used filleting wax to build edges where I was not sure moulds will release.

And I started with the gel coat, coupling and tooling uni-mould.

After a week I decided to post cure the moulds up to 80 °C as noted on uni-mould pdf.

Then I decided to separate the moulds and it was very very difficult.

I succeeded without to much damages to the moulds (at least the area I need to make the final parts)

I will repair the mould later but I would like to know what I did wrong and was the right way to do it.

Thanks for your help guys