lump of old bus bar out of an industrial distro cabinet , all you need is a lump about six inches long , couple of inches wide and half inch thick if you can get it , or there abouts . ideally a couple or more of those as sooner or later you will bevel edges and put a radius on a corner to get into awkward spots and things , I have about three bits I use for most things , one is a foot long and its great , a six inch bit gets used often and lastly a bit about two inches square , very good for jamming in tight spots , or using on '' the other side'' as a heat sink , but they do get warm quickly , so watch your pinkies.Yes, there will be some new panels wherever they are available. Otherwise it’s hours of tin bashing.
where to source a chunk of copper though? The stuff on the bay looks too small.
tia.
Even if you have to go down to the local scrap metal dealer and buy it it will be money very well invested.