Thanks Clive

I would have thought there are other benefits to mounting the rails on top too, like the slider bearing are being worn either side rather than all the weight and action being applied to topside...................Although it is probably negligible over time anyway.

I like the Frame, neat job, is it 75mm box section your using or is that 100mm? ( I was trying to guess from the clamps and mdf).

Epoxy, I haven't specifically looked yet but I did see some where making Epoxy square pads, but what you have done there is much better, less chance of the epoxy shattering with long strips like that too as opposed to isolated squares.

I got a load of Epoxy here...and I guess besides a slow cure pre warming will make it like water to get the level, in fact you can get laminating epoxy which is quite thin and you buy the slow activator...(I repair boats occasionally). I buy from East Coast Fibreglass supplies, and CFS fibreglass suppliers.

How are you sealing the MDF mould to stop the Epoxy running out underneath? have you stuck it down with a grab adhesive or some sealant?

I make grp moulds occasionally and I use modelling clay (the GRP suppliers sell it) to make fillets around edge. you never see square edges with GRP parts, always rounded,,and it is done with modelling clay and a wooden spatula,,,or finger to make smooth radius. (Though in the case of what you have done there it wouldn't be applicable because the radius would create a lip in the epoxy down the edge). Anyhow just thought I'd pass that on as the clay is handy for various temporary shaping and sealing once you have used it for that kind of thing.

Some polyurethane glue like gorilla glue, or even an expanding foam gun would make a good seal too,and be easy to peel off afterwards.