Just last week I decided to tinker around in my garage and try making percussion caps that would fit the nipples. The aluminum sheet I had on hand was too thin. One of these days I'm gonna get some copper sheet and try again.
I don't know if the hammer has enough oomph to set off priming compound or not. But I'd like to find out.
Mine is an older one with a fully rifled barrel. Just have to finish drilling tiny holes through the nipples and it could fire. .177 round lead BB's seem like a perfect fit, and a pinch of Swiss Null-B priming powder aughtta be suitable for the charge. No real practical purpose, but I just think it would be cool as heck to actually shoot one of these.