Now it's just a matter of applying glue, I used Elmer's® Carpenter's® Wood Glue, clamping it and letting it dry.
The fit was so snug that I just pushed the drives in and they're staying put. If it's a little loose you can easily dab a bit of hot glue onto the end and the sides of the drives and use that to keep it in place.
So now you have a double-ended flash drive. Carry your digital life around with you and take on everything.