3D printing isn't really going to work. Think about how 3D printing works, and you'll realize that you can maybe 3D print a prototype, it'll feel like horse ****. The slider will have ridges every which way, and will have huge tolerance issues. Casting is the only way to really proceed.
Pine vs Bamboo is the use of small slits in the top casing of Alps switches. Newer switches (simplified, etc) don't have these. I have no idea how the slit can have such an affect, but it really seems to. I assume there is more to it, but that is to be determined (Hypersphere?)
Building these switches is not going to be easy. If you want to make the switches MX compatible, look at the i-rocks did with their new switch, which is similar in idea to what you're saying. To do this correctly would take a great deal of R&D to iterate with: multiple small variations to the tactile leaf, ensuring it is correct in each case; small changes to the geometry of the sliders to accommodate the keycap: this is all hard to do. Things like getting the switchplate right is easier said than done.
You'll need to be pretty dedicated to pull it off, and I wish you all the luck in the world. I would love for this to actually happen- I love the feeling of Alps, and getting newly made, high quality Alps-likes would be exquisite.
Hell, just designing a case that is a bit bigger to accommodate a cherry-style slider would be neat.