JonnyB, Jim Villers had his setup at the Charlottesville PUB in 2017. He cleaned and tested many injectors, and I remember helping at least one member removed them from his car and replace them. It looked pretty identical to the one shown from Mercedessource, basically some connectors, hardware, a supply of cleaning fluid, and a gauge/pressure pump.
I don't have any to check but if YOU do it might be worthwhile to build one.
The cleaning process basically puts a little to a lot more pressure on the injector than it gets from the FI pump. This can "free up" any stuck parts, but not 100% of the time. I remember watching as we pumped and finally a stuck injector "popped" and began to spray. Then continued spraying and pumping allowed the fluid to clean the injectors.
This is a great PUB topic and I think we'll do it again for 2025 if we have a PUB tech session...