Watch out for player piano kits which I have seen in the past, made
from aluminum extruded parts and containing a soft vinyl rubber valve.
They are highly cantankerous and unreliable. Notes stop playing at low
volumes like magic, because the valve is, in effect "sticky" to the
aluminum surface. Its stem is soft vinyl and sticks to the edges of it
lower valve seat, and whatever direction that valve is angled at when
the pouch pushes it up each time is the degree that it is able to seat,
because once it touches the outside valve seat, it has two sticking
points:  the side of the stem where it touches, and the spot on the
outside seat. From there, it cannot slide to seal. So the owner will
have to turn the thing up full volume just to hear all the notes
perform correctly.

Also, since the pneumatics, which are also extruded aluminum, have a
built-in hinge, they tend to tear their cloth at the hinge end and leak
badly in short order. The reason is because the molded hinge must be
recessed, so it acts like a lever, stretching the hinge cover and
pulling it off the thin metal leaves, or pinching it continually until
their sharp edges have cut completely through the material.

I don't know who makes these things or if they are still being made,
but they are absolutely miserable in my opinion, require a lot of
vacuum to run, and are just no fun to listen to or keep up with, as far
as their problems are concerned. There is no way to fix them, and they
ignore good player technology for a quick and dirty method of
assembly.