Best way to precisely cut a Sheet Metal Computer Case for a cooling mod?

I'm modifying a computer case for my brother. We are discussing several mounting options and are needed to find a way to easily and precisely cut the sheet metal of the case. And inexpensive too if possible (under $100).





We need to be able to cut out precise squares without damaging the metal around. For cutting out circles, we have figured on wood/metal holes saws.Best way to precisely cut a Sheet Metal Computer Case for a cooling mod?
Find any asbestos in your Eureka Ez Clean vacuum lately? have another look behind the hepa filter.





It says referb and then has a sticker on it.... wonder why containers are coming from East with asbestos plates inside and shiny stickers outside?





Take your project to a sheetmetal place and they will probably cut it out for free for you if you buy the metal there. Make it out of copper it would be freaky cool.





Did I tell you I found 2 pieces of Asbestos type material in my Eureka Vacuum I bought. Pretty odd, going to get them tested for sure!Best way to precisely cut a Sheet Metal Computer Case for a cooling mod?
If you have only a few to do a nibbler tool will work. They are available at RadioShack. They cut clean but are a bit slow.





For round holes a chassis punch works better than a hole saw. They are available in sets for smaller sizes at a reasonable price, Larger sizes get rather expensive.





These are the tools that ham radio and electronic experimenters have used for decades. They work well with nice clean results. A dremel tool will work but don't expect to get professional looking results.
You can get a cutting disk for a drill motor to cut with. Tape off the entire area first with masking tape, draw your outline, then cut.
I think you should use a ruler and draw lines that you can see, but wont disturb the Metal
I would go with the dremil and perhaps a cut off wheel.