Projects like this can be great teachers. Sometimes they teach you new lessons, sometimes they remind you of old ones. And sometimes they're just exercises in dealing well with things you can't control. Here's a smattering of my lessons from the Nookduino.
The big one - well, two smaller ones that add up to a big one. I decided to use a Cypress CY7C65213 instead of an FTDI232 for several reasons. I also neglected to analyze the power circuits too discerningly. Had I done this, or paid more attention to https://community.cypress.com/docs/DOC-10995">this comparison, I would have noticed that a)The Arduino Duemilanove does not have a dedicated 3.3v regulator, but instead relies on the FTDI chip for a low current 3.3v supply and B) the cypress chip does not supply 3.3v, but instead an 'unusable' 1.8v supply.
My fix was to not solder in the pin on the 3.3v header and use some small stickers to cover up the 3.3v silkscreen. Not the greatest, but at least it wont destroy anything.
If I had it to do over, I'm not sure if I'd just go with the FTDI, put a dedicated 3.3v reg, or just not have that pin on the board.
There's a resistor in the schematic for the original Duemilanove (R2) that I ordered and installed on the first board. Turns out that it's a DNP part and actually breaks upload if installed. I spent way to long thinking I had not installed the chip USB-Serial chip correctly, and it wasn't until I looked at an original Duemilanove that I realized my mistake.
I got a stencil for helping me assemble the boards. It worked out pretty great, but I wish I would have added some mounting holes. I'm not sure that mounting holes that match the Nookduino would have been the way to do, but something further out tht was pre-measured could have been useful.
I don't know that I could recommend my 3D printed frame, but it worked out surprisingly well for my purposes.
I'm still not sure if there was anything I could do about this (other than buy PCBs from another supplier, but the registration on the silkscreen is slightly off. For most parts it's so minor that you can hardly notice it, but for the mix of silkscreen and copper for the nook face, you can tell.
I used the PAM8501 1.5w amplifier based of the Adafruit Circuit Playground Express design. It was ideal because there was a tiny nook that I could fit the chip into, as small as it is. The chip is great for tones, but for the Talkie Library it's just a lot quieter than I'd like. Since the audio feature was am afterthought and it still does what I set out to do, I'm not too broken up, but if I ever make an audio breakout I'd really like a higher power amp and something with some programable gain control.
For having worked 2.5 years at a 3D printing company, you'd think I'd be better at printing. I just ran into a lot of 'gotchas' when trying to do stupid printer tricks.Early in the year I upgraded my printer to a Duet 3 which I love, but I jumped into some production printing for another project before really dialing in the new board. Even after production ceased I just coasted on what I had. I think that might have something to do with the oddities I was seeing. Either way having to reprint initial gcode and not being happy with results definitely cost me some time.