Ordered the parts for a TSNM last week. PCB came yesterday, so I spent the next 10 or so hours furiously soldering.
Sadly my Teensy was DOA, so I have another one arriving tomorrow.
Thanks to @stripes for pointing me to @shellfritsch, and the later for his Octopart BOM - which was a very helpful starting point! Also, thanks @polyoptics! I think you asked a lot of the most obvious questions that I definitely had. 
One question for those of you who’ve tackled this:
My encoder is just a smidge too tall for my tastes aesthetically. I did the nut-spacer-thing the build guide asked for and squished the hell out of the encoder to get it as low as I could. Did I get weird results, is this particular encoder weirdly tall, or is it just awkwardly tall by design?
If this reminds you that you wanted to tackle this project, here is an updated BOM that as of my purchase had everything available. YMMV. It’s a lot of work if you’re rusty or new, but it seems like a good beginner SMD project (it was my first)! The documentation is very good, and board layout is very clear.
https://octopart.com/bom-tool/45OT0qq0
Post-Shower Edit: I forgot 4 things that are not in the BOM:
Knob and Cap for Knob (the same one used in the reference build):
The cap looks pretty flash if you paint it gold, as I have. I also think a white cap would look nice. I have a couple of spares too.
Also:
Additionally, you need a 16-pin power cable, which most modules do not use.