Pair of old windscreen wiper blades
Steel wire (not stranded)
Step 1: Take the rubbers out
The metal strips could possibly be used instead of the steel wire later.
Step 2: Cut slots and slot blades together
Slot the other blade in to the slots at right angles. Depending on the accuracy of your cuts, the tension may or not hold them together. If so, great, if not, never mind, the wire hook will hold them together later.