I've sourced some materials, going to measure those up when I can - hopefully got some stainless on the way too, so I've got a bit of choice! I think 2mm will be my absolute limit when it comes to thickness, though I think that might just about do it...

As for construction, the idea was that I'm going to have a box of 20mm HDPE that's all attached together, bolt the scoop to the front of that, then bolt the lot (probably the bottom of the scoop too) to a baseplate. Within that box I'm going to have some internal supports/separators that'll also be HDPE, and if I can't bolt the drive to the baseplate enough, I'll probably attach it to the HDPE. I've got a paint diagram somewhere that I'll probably upload in the morning...

Been out and got some screws too, mixture of M6 and M8, and between 40 and 100mm long, the m8 100mm ones are going to be for the main structure, M6 being for the baseplate and lid. Got some epoxy too to potentially glue the drives to the base or the HDPE. Might not be the best solution on its own, but any help I can get to make the things stay where they're supposed to can't be a bad thing!