Can I sell in "lots"?

I am opening a wholesale site, for clothing items, and intend to sell some items in lots only. But I want the customer to be able to select different types of the product to make up their case lot.

For example:
T-shirt "A" is sold in lots of 10 only. BUT you can mix up the sizes in the order like so:
5 size Small + 2 size Medium + 3 size Large= 10 total items in the lot.

Is there a way to customize the buy box or something (like with multiple quantity boxes) so they can put how many of each size they want to make up their lot of 10? I am using Zen Cart v.1.3.7

Hmmm... that's an interesting predicament.

Yes, what you can do is create three different options one for each size a small, medium, and large option, make sure they're "text", this way the user can enter the numbers of small medium and large that they want.

The only downside to this, is that if they don't add up, it won't tell them, and you'll be left guessing what they want.

You're talking about using a textbox attribute for them, right? (just clarifying).

But if I did that, the cart would let them checkout even if the mandatory 10 items weren't reached too, right?