I attached my op amps and washers pretty much the same way. I had to break down the ceramic insert on the back with a high speed steel burr and then used a carbide endmill to mill out the shell. I think because of what a nightmare it is to drill out an op amp, it's pretty likely the originals were actually TO-39 transistors. I used an M2x5 socket head screw with a nut on the inside of the clamp. This way the clamp can be slid onto the Roman's adapter I use without any modifications to any of the parts.
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Also, unrelated, I took some shots of the saber today as I was taking a photo of how the op amps were attached, so enjoy! It feels good to have it functionally together and finished, at least until I can get a real balance pipe. That being said I'm pretty happy with the weathering I did on my Russrep balance pipe so I'm content for now!
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And last but not least a moody shot of all of the components.
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Beautiful+1 build buddy, my vintage Obi is at the same stage, we sure need a new engine to complete a few builds