The most damaging fragments come from a radial cone of ejected fragments from the middle portion of the work coil (where the coil-coin repulsion forces are strongest). The total overall cone is perhaps 30-40 degrees wide. If your electrodes are not directly interception fragments within this cone, there's fairly little very little wear from flying fragments. I use copper bus bars, with bolts and flat washers made from silicon bronze. Pinching the coil wires between the washers reduces bus bar erosion from sparking during high-current peaks.
I use 1/4" and some 1/2" thick abrasion-resistant steel (AR-400) plates to intercept high-energy fragments that are in the direct path from the ejection cone. These are replaceable as needed. The outer walls of the blast shield are 1/2" thick Lexan polycarbonate. I also use a big chunk of 1" thick AR-400 with a semicircular cutout to intercept the high-energy coil fragments that would otherwise hit the floor of the blast chamber. The chunk of steel absorbs the most of the momentum and kinetic energy from the downward-flying coil fragments.
Unfortunately, I'm on the road for the next few days, so I can't take any pictures of some of these assemblies.