Buying strip brass

A springy battery contact is possibly phosphor bronze.

Cheers

I suspect you want phosphor bronze, rather than brass, if you want it springy. Thickness is difficult to say without being able to know how springy you want it.

You can still buy the old 4.5v batteries although I think it is a phosphor bronze rather than brass (try Wilkos or Amazon). You may be able to get offcuts of brass strip from your local model engineering club if you don't mind what shape they are. Won't be as springy as the right stuff but it will probably work ok for long enough to be useful.

I disagree about it being phosphor bronze on throwaway batteries - too expensive and you could easily make permanent bends in those strips for some torch applications. Plus they were the wrong colour for PB which is a bit more coppery than plain brass.

Springy enough to keep an electrical contact yes but not really a spring in the sense of operating in a mechanism, where phosphor bronze is the correct material to use.

I suspect the gauge on the "flat" torch battery would have been about 24 SWG.

I think that would be around 10-15 thou.

is that 0.4mm?

This is what you should find in a decent traditional model shop.

For springy you may need a phosphor bronze.

is probably a good bet if no model shop nearby.

For small amounts of materials Ebay can be quite good. For those who don't have a fabricator nearby who might sell offcuts.

Thanks for all the comments. I think the phosphor bronze suggestion is key. Or possibly nickel silver.