It looks like I got away with my mistakes from last week - I left the catalyst out of the gel-coat! The correctly catalysed layers of chopped strand mat managed to also cure the gel-coat. The result isn't pretty, especially as I also forgot the surface tissue in some areas. (In the picture below, you can clearly see the fibreglass strands.) It is, however, structurally sound for use as the air boot. It will require a bit of gel-coat filler to make it look presentable.