Hey All!
I am new to case modding and am not sure what to use to cut a 1/4" hole for a 15 position d-sub connector in a GBA.
What I am doing is trying to make room for the controller input that I'm just about finished up making. My main problem is that
I don't have a dremel...as I've heard they are good for cutting plastic. Would a Xacto-Knife suffice? Should I go the heated kitchen knife route or will that look bad? Any help would be appreciated!

You can use a drill to make holes within the area you want cut, and sand the edges out. Or, you can use a small bit and cut with it.

When drilling thin plastic, remember to keep the bit spinning fast and drill against a piece of scrap wood like a chunk of 2x4. (Drilling a pilot hole with a smaller bit helps too.) If your drill bit is turning too slowly, it will bite the plastic and rip jagged chunks out. The idea is to scrape the hole out with light pressure and fast bit speed, not carve through it like wood.

If you need a square hole, draw it out on the plastic, then drill the bulk of the unwanted material out with a bunch of holes like this:

[OOOOO]

Then you can square the corners out with your knife.

When using a non-serrated knife to cut plastic, treat it as though it has teeth and saw up and down a bit. Just pushing harder to slice through material only leads to blood loss.

Thanks guys I'll try the drill. I'm sure I have one laying around here somewhere
Oh and the detail will really help thanks again!

I made a subminiature connector template earlier.

docs.google.com2011.04.05.pdf.

Print it (with no scaling) and then tape the part of the template you want to use to your piece.

I used a 3/32 for the corners when I drilled mine out, and used my fancy work knife to cut the faces out (accidentally), though I was originally planning on spending half an hour poking at it with a saw blade.

Thanks for the templates, but my 15 position d-sub is 3 rows. So basically the standard VGA input/output but thanks for the help! I think I'll just buy a dremel...

Oops;
Well it uses the same shell as the DA9.

Also, I've been told that spraying the plastic with soapy water helps with the plastic melting to those blades. Haven't tried it myself though.

I will have to give that a try! I've ruined many a Dremel bit with a melted plastic wad on the tip of the bit.And those bits are expensive...

So I ended up buying a cordless Dremel from Lowe's and, while the battery lasts only about a constant 30 minutes, the overall performance of it is great! Just what I needed. I have a drill but I was just worried I would mess that up really badly... but I am almost done with my NES controller to GBA mod thanks to the dremel