As long as this thread is back;

I've made several metric allen bits for both 1/4" and 3/8" square drive ratchets by cutting pieces off of L-wrenches with a cut-off wheel in a Dremel and super gluing them into cheap sockets. It's much cheaper than buying ready made bits and replacement bits for the smaller ones that wear out quickly are easily made. In fact, you get two for the price of one by removing the worn bit (acetone dissolves the super glue) and reversing it in the socket.

Just feed the L-wrench into cut-off wheel slowly and with little pressure so as not to overheat the metal and dip it in cold water every few seconds to preserve the temper.