I recently purchased the 9 card holder from a local craft store. I've cut my paper several times to the size of 2.5 x 3.5 and it seems a bit too small. Can someone tell me if that is the correct size for this holder and if not what is th correct size? If they are to be cut @ the recommended size, what keeps them in place. This is my first attempt at ATCs and I thought it would be a great gift.
Thanks for your earliest possible response.

Is that the printer's tray that you are referring to?

If yes, you have to glue it down.

For the size, just measure it. It may be slightly larger than an ATC to allow for extra bits on the ATC itself.

I used Tombow multi liquid glue to adhere the paper to the tray.

I just posted this altered printer's tray - not ATC but same idea.

Altered Printer's tray for Scrappymama6 By Corrie Fan