So last night I used the Dremel to make the syringe slots, and with that, the shells are ready for the next step which is finalize the pop-up electronics and build the boards.
Amazingly, I had all the right bargraphs I wanted on hand. Here's a test fit to see what the cavity for the electronics shaped up like. It looks like there is enough room for the plan.
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"However vast the darkness, we must provide our own light."
Stanley Kubrick
"Tomorrow belongs to those who can hear it coming."
David Bowie