The next job was to add the IR LEDs, acrylic and mount the IR camera underneath. I'd already soldered a series of LEDs to some breadboard, but was having difficulty mounting them into the holes in the U rail as they weren't all perfectly straight. So, I ended up using connector blocks instead.
The U rail is fixed in place with No More Nails, which is frighteningly strong. One side is left open for the moment so that the acrylic can be removed for access to the monitor. Once everything is ready I'll close the gap.
Another view of the underside. Things are looking a lot busier under there now. The LEDs are all wired into a molex connector which will plug into the PSU for the machine that will be powering the table.
Here's the first test grab of interaction with the surface. This was before I had added a visible light filter to the camera, which is why there appears to be colour in the image.
Although the blobs show up really well here, they are much less visible while dragging. Going to have to add a compliant layer to the acrylic to resolve that.