The needles are a nice push fit, well I used the drill press for extra force
Cost breakdown for hardware is as follows: (excl. tools, time, beer, etc)
*8mm polycarb - offcut, free
*4mm acrylic - same
*4mm copper base - pulled from a 'borrowed' IGBT power module (big one, probably 600A or more
)
*25 disposable medical needles 1.25x40mm (not used! ) - 1.5€ (+ a little embarrassment - make sure you're the only customer if you buy these at the chemists, lol)