I'm using 18mm chipboard for my front, i had it lying round - you could use 18mm mdf i cut a cardboard template then chopped it out of the wood
now the messy bit, get some gloves and a long sleeved top at a minimum, a good mask is useful too. pre cut fiberglass matting in the shapes you need
then brush the tape with resin and let it go slightly sticky then add the matting and more resin, dabbing with a 2" brush,
i mixed my resin in small batches due to the heat.
once the first coat starts to set, or 'tack' you do the same again with more matting and resin, repeat about 5 times
when all dry, pop it out lol
Jake