Right as far as I can acertain (sp) the tray is ABS and varies between 1mm and 2mm in thickness. it relies on the floor for strength. The glue I used is a general purpose solvent glue loved by modellers, this is a heavy duty version which also does ABS and melts the plastic.
When removing the tray it ripped in two places, now I glued (solvent welded) the two splits then the following evening used PP gelcoat filler over them - I also reattached the punched out part of the tray with the same technique.
This afternoon I covered the whole stand on area and the sides with a layer of carbon fibre with a second layer of kevlar over the drain hole.
I also was able to drill out the hole but I just did a couple to see how easy it is.
Tomorrow I drill out the whole drain hole and gelcoat the rest of the rips, I will also sand down the current repairs first.
The gelcoat around the drain is a bit difficutl to sand but I will do it first.
I hope to refit the tray next weekend as I need to add more support wood, add a drain for the inside of the toilet as spilt flush water cannot be drained (the poo and wee goes into a cartridge), I also need to repair a crack in the bowl unit.
The toilet is screwed through the tray and into the floor, this prevented me from using more than 1mm of support except over the hole.
When complete I will push GRP paste up around the drain to definately stop any more punch throughs on the drain.