After building the first Baby Ten Sequencer, it became clear to me that one, sequencers could be powerful, and two, there was a lot of potential in this type of circuit. So, I ordered a set of core Klee Sequencer boards from Electro-Music (highly recommend their forum, by the way). I soldered in some resistors and diodes from what I had on hand, considered for a moment perhaps doing a panel and hand-wiring it... then found out that NV from the Muffwiggler forum had worked up a Eurorack panel and daughterboard.
I ordered a full kit from Synthcube, which does not include the core circuit boards from electro-music. This... wound up kinda painful. The kit plus shipping cost enough that New Zealand Customs stung me for money (the threshold is $400NZD, shipping is included in this)... and when I opened it, I found that it was only a parts kit -- resistors, chips, but no PCBs, panel, or the cables. The box had been marked FULL KIT on the customs docket, but was in fact just a partial kit. I emailed Synthcube about this, sent back the parts kit, and they shipped me a real full kit, this time. Luckily, Customs didn't notice this second one. Not very impressed at all by the service.
I spent a productive weekend once it arrived doing a lot of soldering.
See those interboard cables with the crimped connectors? Big trouble. Big, big trouble. The Muffwiggler forum thread on NV's boards for the Klee mentioned that a lot of other people also had trouble with intermittent connections using these cables, and some people recommended stripping a couple millimeters of insulation from the end of each individual wire, and hand soldering the end of the wire into the metal that is supposed to cut through the insulation. I wound up doing this with every single one of the buggers. NV did a later revision of his Eurorack Klee boards to remove these entirely (along with, I think, a redesign of the core boards.) The sausage-looking components on the left are precision 0.1% accurate resistors, by the way.
Here's an article explaining the sequencer.