On Sunday, 20 January 2019 12:29:14 UTC, jkn wrote:
Some sheets of 2mm Alu would be nice, guillotined down, but that looks
a bit pricy unless I happen across some.

There's a skip near me full of almost new 4' or 5' fluorescent fittings that are being replaced with LED. Ample source of powder coated steel or aluminium.

Not much help to you, but that's the sort of place to look. Shopfitters and strippers-out of vacant premises.

Owain