You can easily get a 3/8" Male to 1/4" Female stepdown adapter that will let you use any 3/8" drive socket on a 1/4" drive ratchet or torque wrench. Any hardware store, Sears or Home Depot/Lowes has them.

Making your own Alen bit sockets is easy if you have a Dremel tool with a cut-off wheel. But a set of L-type Allen wrenches and cut off a 1" or so piece from the long arm using the Dremel. BTW, you cannnot cut even cheap Allen wrenches with a hacksaw so don't even try.

Use the straight sections in regular metric sockets as needed. If you want to make the bits more permanant, superglue or epoxy the Allen sections into a cheap set of sockets.