Mostly for dianalo, but also for anyone else this might help!

We have a wall-mount faucet, and wanted to keep it. However, we also wanted shut-off valves for the water lines (I think our local plumbing code actually requires these)---but we didn't want to have the pipes come out of the wall for the shut-offs, take up cabinet space, and then go back in again.

To solve this problem, my husband (who is new to the DIY stuff, but interested in gadgets and how things work) came up with the idea of framing a little box to contain the shut-off valves that we would then plaster around. He built it himself (first time using all the woodworking power tools!) and it works perfectly. If we'd had a contractor, I suspect we could have made it even prettier/cleaner looking, and also would have put a hinged door on it. The cabinetmaker cut out a square in the back of the sink cabinet so that you can reach in and use the shut-off valves.

Before (DH ultimately moved the brace you see in this photo to be underneath the shut-offs in order to fit his box in):

During--didn't take a photo earlier unfortunately, but the edges of the opening are made of four blocks of wood, cut from a 2x4 and drilled into the studs, with a piece of plywood for the back, all fastened together with L brackets. We then plastered around the edges of the box. (We did have to drill out notches for the pipes in the 2x4.)

And a little later, finished except for cabinets:

Also unfortunately haven't taken a shot with the cabinet installed yet, but basically now there's a sink cabinet in front of it with a hole cut in this space so that the shut-off valve handles have room to turn on and off. You would need to position this to be accessible once plumbing is in place---our plumbing was super simple so that was easy, but if you have a lot going on below the sink, it could be trickier. But it takes up virtually no space in the sink cabinet itself, which is perfect. (We have an undersink trash cabinet, so it was important to have as few lines as possible running through that space---we ran the dishwasher connections through the toekick space except for the power, so the only thing really in play in that space is the drain.)

Our version of this is not pretty at all, but totally functional. I think you could make it less utilitarian looking fairly easily, though---you could have a little hatch opening into the sink cabinet, provided it would clear any plumbing (we have no disposal, which helped) or even a little curtain to hide it. Had we come up with this idea before running the new plumbing, it would have been trivial to build in the adapters to put Tapmaster valves in-line with this too, but since we put it in after the fact, it was too complicated to deal with, so we skipped the hands-free faucet. Boo!