The brass corners were attached to the blocks using no.2 * 3/8" countersunk brass wood screws. A marginally longer screw would have been better, but I wasn't able to find a supplier of longer screws at that diameter.
Before adding the corners, the blocks were treated with 2 coats of beeswax. There are 10 of each colour - with sufficient unused blocks to allow for a third colour.
One problem that became apparent is that the legs were incredibly tight onto the blocks, and thus were difficult to stack. In order to combat this problem I began the process of removing a sliver of wood from the top corners to give more space for the top block's legs.
Finally, each leg is connected to a wire which is inserted into the pilot hole for the lower screw. These wires are colour coded for positive and negative and are wired diagonally opposite, so that it doesn't matter which way round the block is placed.
For this initial incarnation, the wires are connected to a resistor (a different value resistor in each block). The system is thus able to determine the value of a block added into, or taken away from the block.
However, I incorrectly came to the conclusion that this was not the case and that the electricity took the path of least resistance, because the differences in resistance were not easily measured (certainly by my circuit).
That's it for now … still to come - a video of moving the blocks causing changes on the screen, and where we go from here.