Boxes are complicated with shipping

What size envelope do you use for baseballs? 9 1/2 x 14 1/2" or something smaller?

For items like baseballs and golf balls I use a padded envelope.

You can always send it in a box, then use a padded envelope (given that your items all fit nicely in the envelope) for SASE.

If I sent non-flat items, should I send it in a box or padded envelope? The box seems like a better option, but I wouldn't be able to fold up another box of the same size to include it self-addressed and stamped. I would need to send the items in a bigger box just to be able to hold the smaller box. The only other option would be to include a label, and have the celebrity use the same box I sent to them, just cover up the label on the box with the one I provided. That assumes, though, that the celebrity kept the box and didn't destroy it while opening it. Plus, they would have to figure out that they should use the same box, unless I specifically said in the letter to do so.

I seen a success for Greg Maddux where a baseball was signed, and the picture has the return envelope. A padded envelope would be easier to include a self-addressed padded envelope since the envelopes fold up. It might be a good choice for baseballs, but basketballs, footballs, and baseball bats seem too big to fit in an envelope.

Should I do envelopes if I can, and then bigger boxes with smaller boxes inside when I can't?