Oddball size prints

[gardener]

I have lots of moon shots that a garden friend would like 3"x3" copies of for some type of little Lazy Susan (rotates 360°) type frame she already has. The shots are for her 12 year old grandson aka amateur kiddo atronomer and while I can easily resize the files to a 3"x3" size for her to have printed at her local Walgreens or whatever, I have no clue what to tell her to ask for when she has them printed... It's a freebie on my part as I'm more than willing to help urge a young person along in his or her hobbies/studies but free or not, I still want them to come out right.
I've already mentioned that at the small size, I doubted that very little crater and other features would be that visible but apparently, she's more interested in the moon phases than the actual detail of the moon...
So... what would you normally ask for when taking them in to be printed? Tell the processor to retain the actual print dimentions but print on 4"x6" sheets and just cut down yourself with scissors afterwards? Configure all the shots to fit on some other standard size like 8x10 or 8x12 or 9x? and then cut apart afterwards? We're only talking eight pics here so cost won't be great any way you go. She'll get a CD with the sized files from me and that's about it since I'm here and she's in California.
The friend is quite elderly and while she has a computer, I doubt that she has the processing options to play with the actual files so as to configure them one way or the other and that's why I'm trying to do as much of the pre-work as possible before sending off the stuff.
Advise please?
Thanks
Steve W

[Daniel Bates]

You could just make new files with two 3x3 photos on one 4x6-sized canvas (leaving the rest black so she can cut them out). Then Wal-Mart or Walgreens or whatever would just print at their normal 4x6 size, and you or your friend would have to do some trimming.

[gardener]

Well duh... why didn't I think of that... I just got wrapped up in some complex sizing arrangment in my mind and just never got back to the obvious simple solution... Thanks Daniel!