Hi,
I thought I’d drop a few lines on an MBSID build into a C64 datasette using one nanosid (i.e. swinSID). I had leftover parts from my “main” MBSID build; I had originally planned to build four cores, but I couldn’t fit them all into the C64 case that I used. So I had all the parts lying around except for an LCD, which I now decided to get, and put the parts to good use.
I had two SID module boards from Mike, but in order to save space I decided to etch my own “double SID PCB” (and a DIN2 board as well) using the laser printer + clothes iron method. This was my first etching project and maybe the quality could have been better, as I couldn’t get the other half of the double board working. So in the end I just made it with one sound chip, I hope I have time and energy in the future to redraw a complete core + 2 sids PCB with Fritzing or something for an optimal fit.. and anyway it’s good that all projects are not finished immediately 
At the moment the datasette insides are a mess, as I guess with most of these modular builds. But it works.
I decided to use nanosid instead of the real thing because that made voltage supply much easier – you just need one regulated 5VDC for both the core and nanosid. Plus it’s less noisy than a 6581.
I kept all of the the datasette’s buttons to have them push the actual MB buttons 1-5 + menu. The core PCB regulator (follow the red-white-black wires) is attached to the button plate for heat sink purposes. The two buttons on the right that are hanging loose (Up & Down) will to into the counter hole once I get my hands on a hot glue gun… the LCD is attached to two screws that I hot-glued onto the datasette cover.