I've seen a few of these from a russian model forum and they look quite useful for drilling smaller holes efficiently, sure you could probably use a router but they're a bit big when using 0.5 drills, does anyone have any information on them or how to make one? (images can be found on google 'Diy motor drill' theres a few images to give you an idea of what im talking about https://www.google.co.uk/search?safe=off&q=diy%20motor%20drill&psj=1&bav=on.2,or.r_cp.r_qf.&bvm=bv.50165853,d.d2k,pv.xjs.s.en_US.seW1cfrvSKg.O&biw=1152&bih=628&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=wBH9UYTENK7J0AWU7oHYAQ)
(from jack aubreys gallery, hope he doesn't mind)