If you've got a drill and a jigsaw you can make do without a rotary tool. (an actual "dremel" is more than £25)
Use the drill to make a starting hole and the jigsaw to cut out the window.
Thing you'll needf to add to the list/calarify
Lowtak or masking tape
3M cleartape 4010 (very good double sided tape)
Jigsaw Metal cutting blades
Carpentry Square (this is a
tool )
Bill Owen did a very good video on makeing a case window
http://uk.youtube.com/watch?v=WpZoE-zj0-k
Also did a tutorial for getting a mirror finish, probably don't need to go that far but the basicas still hold true for painting
http://www.mnpctech.com/case-mod-pai...od-how-to.html