LF - Heatsink - for a dyi led setup

[ckmullin]

I'm thinking about changing up LED's with a new setup and want to do the dyi method. I'd need a heatsink something like 8 inches x 5 inches x 1 inch. (dimensions are not exact as the plan is evolving but that's a good start, I can easily cut down if needed) A couple of 4 inches x 3 inches won't work as I want a solid 7-8 inch piece.

I'll buy online if needed but thought I'd try to source it locally. If you had something that might be close give me a shout.

Thanks