Jan wrote:
|| I have a slot (cut in the case of a fully assembled computer) about
|| 90mm x 10mm. I need to extend the slot to about 94mm x 10mm.
||
|| Is there a tool that would do this cleanly, without making any metal
|| filings such as would be caused by a metal sawblade or drill bit?
||
|| If necessary, I could get away with making two 4mm-long slots at one
|| end of the existing hole, and just bending the metal between the two
|| slots, instead of cutting it away.
||
|| The clearance available for getting any tool into position is a 6mm
|| wide strip around the slot perimeter.
||
|| I want to avoid metal filings, so I can avoid having to take
|| electrical parts out of the computer case.


They look like this. these are pricey so a good second hand tool shop is
your best option.
http://www.lawson-his.co.uk/images/Q-Max/q-max.jpg

--
Grouch