as above i started using permagrit tools a couple of years back and they are awesome, if you are cutting out small holes in parts, then drilling out the holes then using any type of sanding barrel for a dremel should work.

ok guys what you suggest for bigger holes?

A cutting disc followed by a round file... 

Not a cheap solution but if you have a large number of holes that require precise dimensions the most effective method of cutting an carbide tipped annular cutter.

can you guys get images or links as im not englishman

http://www.tradekorea.com/product/detail/P243135/Tungsten-Carbide-Burrs-.html

you mean these i think these for wood?

I mean these:

Copper Head

http://en.ankatools.com/products_detail/&productId=60.html

They are made for magnetic drills for metal working and can usually be found at welding and metal working shops. I worked for an Americas Cup team and we tested a number if different hole making methods and these were hands down the most circular and dimensionally stable

yes but that to drill not do do angles and shapes. Guys lets drop some links as you know to all of you this is important information!!