Hi,

So trying to get some seams to fit together better and I was wondering if anyone has tried mini-planes?

Like these ones..
http://www.leevalley.com/en/wood/page.aspx?p=64300&cat=1,230,41182,64300

In my experience, with plastic you're better off sanding on a flat surface for mating parts.

I do use them for wooden models, and they are great. You may also want to consider a plane with a razor blade, which is a lot cheaper and does well for thin cuts (and I do use for trimming plastic parts, but more often sheet/stock when scratchbuilding):

http://www.leevalley.com/us/wood/page.aspx?cat=1,230,41182,41188&p=56750

You can get other ones a lot cheaper too.

I have a mini-plane that, is made by Stanley. The thing is probably about 3 inches long, an inch-and-a-half wide, and about an inch tall. A finger-tightened screw holds the blade in place, and adjusts the depth of cut. I originally bought it for fine-tuning joints in my woodworking projects, but I've found it has a multitude of uses.