Whoa, what a cool idea! I knew you'd be back with more 馃槉.
Apologies for the book-begging, but any chance for a Handhelds Part 3 for Game Gear, Wonderswan, and Neo Geo Pocket? I haven't seen encyclopedias anywhere for them, at least not in English!
Thank you so much for responding! I totally understand, I'm a but if a project junkie myself, so I respect the grind, and I also respect taking breaks and pacing yourself. You should only jump in if it's going to bring you joy!
But if you do ever cover Game Gear, Wonderswan and Neo Geo Pocket in one last Handheld Encyclopedia volume, even years from now, I'll be looking forward to it. Or anything else you do!
Oh, and yes! All printed out in Hardcover form. Don't worry, I kept the volumes split into separate books haha. Can you imagine the binding on the PS2 series? Those are actually the last of your works that I still have to print. Here's a picture of how they look on my shelf! (I'm sure you can tell which are yours) 
Omg you are amazing, thank you for everything you've contributed to the community over the years.
I know it's hard work, and you'd like to pack it in, but could I recommend one final book? There are still several popular 90s portables without encyclopedias available at the moment: Game Gear, Wonderswan and Neo Geo Pocket. You already have a Portables roundup series - how about completing the trilogy to cover these last three?
I've looked literally everywhere, and these are really the only consoles of note left (besides Intellivision, Atari 5200 and ColecoVision) that don't have encyclopedias of their own.
I've printed every one of your books, and would love to round out those last gaps. If a donation would motivate you at all, consider it done.
But even if you do stop here, you've done an amazing job, and I'm very grateful to you.