I’ve just finished a production run of PS-4 camera scanning rigs and put them up on our store. If you are looking for an easy way to set up your camera to scan 35mm slides and negatives, they are ready to go. Currently, it seems to be taking me 3 or 4 months to find enough units to justify a production run, so when these sell out, it will likely be months more until they are back in stock.
More info here.