sudomod

There are websites like glitchdgaming.com and pocketadventures.com that sell common ground boards along with other components to make your build cleaner/easier if you're not using an AiO board.

Definitely a common ground board. Cheap and literally everywhere. In fact, there are even some designs on oshpark (I believe helder put it there) where you can purchase it from a board manufacturer directly and have a couple.

I went to the two websites you mentioned. There are indeed many interesting game parts. I am considering whether to place an order. Any suggestions?

I've recently actually bought stuff from both glitchd and pocketadventures, so I'm comfortable recommending both of those vendors.