There's not much info. about these things here, so I figured I'd share what little I've learned about 'em since picking 'em up. If I ever snag a Photo Reader, I'll amend my findings.
First up is the Illust Booster. At first I'd feared it was broken, as it wouldn't work with Artist Tool on the flash cart. The rom loader utility thing can't use the I.B as a controller, so I tried starting with a regular pad and switching to the I.B., but no go. Apparently Artist Tool has to recognize the I.B. on boot (if it does, it changes "push run button" to "push III button" - there is no run button), and only then will it work properly; I thought I'd have to find a real Artist Tool (or a chucard), but luckily it can find the pad on port two of a tap. Success! It works okay but it's not great: the window is smallish, so you have to pick up the pen and reset a lot, and you have to press rather hard for it to register, making me fear that I'd break it.
Now that I could draw some shit, let's see how it prints! The Print Booster is more of a Plot Booster, using regular pens to draw your art. Unless there's a way to get it to plot each color separately, letting you change pens after each color is completed, you'll get just the one color; there may be such an option, but the only options I could figure out were one where you directly control the pen (like an etch-a-sketch) and printing the whole shebang at once. Here's what my meager abilities could produce (don't laugh!):
The random straight lines crossing over areas are from having the pen pushed too far into its carrier, so try to ignore those. In the first pic, the top left is from etch-a-sketch mode using a normal controller's d-pad, the upper obey was drawn using a d-pad, the moon rune is from the built in text/stamp tool, and the bottom obey and smiley were drawn with the Illust Booster; and the second pic is all I.B. The flat bottom of the smiley was caused by the paper being hastily cut a smidge too wide at the bottom, making the page curl up as it hit the printer's side when it neared the bottom of the page.
Here's the manuals if anyone cares to read 'em:
Illust Booster and
Print Booster