What scale do you customize in? Why? Do you limit yourself to 1 scale?

CCC.

I don't, but I would guess it's a matter of preference, supply and demand.
If you customize, it's easier to do so if you gather bulk of one scale of raw material to work with.

I work in....
Cosplay life size
!2" Dolls
4.5" JLU
1.5" Heroclix

For me, I stick only to JLU scale. Mainly because financially, it's the only line I collect. So I customized that scale to add to my collection.

I've talked about doing one in the DCUC scale, but there's just not a lot of motivation there. I have no problem doing commissions, but I still have to be interested in the property. And while I love the DCUC line, I don't collect them so the connection isn't there.

I use 6" or 4" scale myself depending on which character I'm making. I want my customs to fit scale wise with the rest of the line I've made them for, I do however stay away from 12" I'm not a fan of the scale

4" scale all the way, however I do collect some 6" figures and 8" figures - but would never customise in this size.