[Graham]

Would you be willing to allow 3D bodyshells in Event 1, a lot of older cars are easier to find for 3D printing than by other means.
If you're concerned about the light weight there could be a minimum weight limit for the bodyshell.

To be honest I could not see any models in the Event 1 list which needed to be 3d printed as most are available as in one way or another as moulded plastic or resin, but I have really no objection either, but I will use the same rule as for Area TA71 models which is that they have to be run with a 3d printed chassis. That would be a safeguard in case of “ultra lightweight bodies” and they would have to be dimensionally correct compared to Resin or RTR models.