This handle is designed for a standard deburring bit sold for 3D printer work. I had purchased a deburring tool from the big river in South America, which came with lots of bits, so I wanted more handles for those extra bits. I saw a few models online, but the one I tried did not have good screw threads, and many were rather large in diameter. This one is made of 3 parts, the basic handle, and two parts that hold the bit in place. 

Assembly is quite simple. Place the bit in one of the smaller threaded pieces, with the slot lined up with the raised part, then place the other smaller part over the rest of the bit and screw that assembly into the handle.

You will need one of the deburring tool bits, that are available from various online sources.