I also though that those books where you color with a "magic pen" (a pen filled with water), were *SO* neat and I had a few of those.
I remember having a Flintstones color-by-water book in June of 1986 (when we moved to Florida and were living in our motor home temporarily, but I don't remember a pen. I used a small paintbrush dipped in water.
I still have some sticker sheets from when I was younger
Ooh, stickers. I still have the Real Ghostbusters stickers that came with one of my RBG books (the second, I think). They're stuck on the door of my old bedroom (which is right across from my current bedroom).
I got three RGB books (one per year, I believe) in elementary school during annual book sales where they'd bring in shelves of stuff in the school library.
The first was an adaptation of a cartoon episode (I forget which).
The second was a weird (slightly fictionalized) account of the making of the first (I wanna say second, but it was too early for that) movie, told from the second-person perspective, in which "you" are goofing off in the school library, and some "really familiar" guys walk in and offer you a special effects position on the film.
The third was a how-to manual. I remember quoting part of it to my dad (back then, I thought my parents naturally cared about this stuff as much as I did, never mind them being middle-aged Polish immigrants

) upon coming home from school with it, and he freaked out with a blurted "What?!?!?!" when I read "nuclear accelerator".