Mounting a painting on a panel

I took an acrylic sketch I had done on a gessoed piece of watercolour paper and trimmed it to fit...

I gessoed a wood panel for a substrate then painted a border around it ina grey that was similar to the painting background...

I slathered the back of the painting and the front of the panel with matte medium, place the painting on the panel and carefully used a breyer and my fingers to push out as much air as possible. I then covered the painting with a sheet of freezer paper (wax side against the painting), laid it face down and stacked books on top of it overnight. I was rather terrified that the freezer paper would stick but it didn't, yay.

I'm rather pleased with the outcome.