I made myself another 3 zone cymbal using a similar method to that used here: http://www.vdrums.com/forum/advanced...mbal-revisited, but changed the design in some ways to make it easily repairable and better-looking.
This time, instead of gluing the two practise cymbals together, they are bolted using small flat-headed screws, bolts and locking washers. The screws are very small and with a little countersinking and epoxy they are fixed to the top cymbal:
I used 5 of them:
Then I layed down the copper on top and bottom cymbals. Another change is that now the piezos go in between the cymbals. I shaved off an area the size of the piezos so they were flush with the surface and linked them with copper tape. Also, I didn't make any cuts around the edge and the triggering is still good, so it turns out it wasn't necessary and simplifies things somewhat.
For the spacing I used strips of 1 mm sheet rubber, the same stuff I use to cover the cymbal surface to dampen noise. It creates a perfect gap, though some experimenting was required to determine how far from the edge it had to stop to let the cymbal flex. At 12 o'clock on each cymbal there are strips of copper that make contact when you assemble the cymbals, to pass down the signal from the top to the bottom without using a wire. That way, when you disassemble them, there are no wired connections that could accidentally get tugged loose.
Next, I covered the top of the cymbal with the sheet rubber (pond liner):
And then covered it with carbon fibre vinyl:
Last of all, I cut out a circle of 5 mm hard poron to fit the centre and covered that too:
Added a project box underneath and that's it. It takes some patience to put it all together, but I think the end result looks pretty OK and it triggers great. One major flaw of the previous design was that if anything failed, as the cymbals were glued together you had to pretty much destroy the whole thing to get at the internals, while now it's as easy as it gets. Also, the glue made the spacing, which is very important, uneven, causing some areas to be harder to trigger than others - now it is uniform all around.