I am needing to understand how a cordless "trigger" works to vary the speed of the drill. Any ideas or knowledge?

I've tried using hardened drill bits but they wont cut the glass. When I apply pressure the bottle breaks.

i was thinking about making a big electric rc plane useing a cordless drill motor is this possible

I need a power drill (preferably corded but cordless is okay too) to drill through light metal. I need it to drill/make little holes on the top of 1:18 scale model die-cast police cars for the light bars. Can you please recommend one? I don't need a high end drill or one with many pieces and tools. I just need one with a tip that will drill through light metal. I am thinking of buying one from eBay but a cheap new one is good too. Thanks!!
What size!!!!!?????

My husband wants assorted drill bits for a present. I find more fun bits for dremels. Can I buy him a dremel? Would it be about the same as a drill. He has a drill but it is not cordless. I thought about a cordless dremel. What do you think?

project

What is the best make metal cobalt drill bits? I`m drilling through 4mm angle iron which has just dulled 4 new bits, slow speed with water to cool. I`ve tried Black & Decker which were useless and Bosh titanium which also failed . I`ve quite a few holes left to drill so need a really good quality bit that will not dull too quickly