hold-and-fold I talked about in a previous thread this tool didn't cost me anything as it was included as part of the kit for the RNAD crew van I'm currently building. It is, however, a very useful tool.
I mentioned before that the body of the RNAD crew van fitted into two slots in the 3D printed floor. This tool is provided as part of the fret of etched parts to allow you to easily check that the holes are fully opened out so that the body fits easily. Once you have done this the instructions say you can discard it, but I realized that it would be extremely useful for something else.
The end of the tool is pretty much the same size (width and thickness) as the end of the Greenwich couplings. This makes the tool ideal for checking that the slot for the coupling is fully open. I had previously been using an off cut of the etched fret the couplings come in, but this was a bit fiddly and had led to me cutting my finger, but this tool works perfectly on my recent 3D printed wagons so I'll definitely be holding on to it.