selling a variation of Accessories with a set quantity

Hello,

I want to make one product with a fixed price that has 30 products combined and the customer can choose whatever he wants as long as its exactly 30 pieces in total.

ex:
the product have x, y and z as options, they can buy 10x , 10y and 10z or they can choose 30x , 0y , 0z or any other combinations in the middle.

I tried some variation option apps but they dont have the quantity limit, and bundling apps didn’t work as well.

what should i do?

please help,

Thanks!