bonsai moms question/help

Ok so I'm wanting to keep two or three moms in my small cabinet (25w/14d/17h). I'm wondering how small of a container could I keep her in? Ideally I would love to keep a mom in a solo cup or equivalent but I feel that is way to small. I have seen some bonsai moms in small containers but would love some advice or direction.

Thanks ahead of time guys!

I had little square pots that are like 4.5x4.5 on top and probably 6 or 7 inches tall. similar to these I would say http://www.htgsupply.com/Product-Kord-Square-Pot---5-half-in-Kordlok-10-Pack . Having a little extra soil is nice when it comes to watering

True. I was went to my local shop today and was looking at square 4in and 6in pots and it got me thinking. Would a solo cup work out would that be to stressful on her.

Also I grow in coco and see a lot of people grow there bonsai moms in soil...is this just preference?