It's tricky getting fan heaters onto exactly the right piece of GRP and this epoxy resin needs heat to cure. The level of heat that comes from two 2000 watt fan heaters like this - for hours. You can tell when it's cured, it starts to get hot as it no longer takes the heat to drive the curing reaction
Here's a neat solution. The tripod comes from an Aldi Lazer level kit that I thought would make chassis alignment easier. It didn't make much difference to that but did show that my workshop, built in 1990, is exactly at right angles to the garage, built around 1880. Don't know how that happened.
The tripod probably regards this as a demotion. The piece of ply was the exit template for the radiator outlet duct.