I'm not at all an expert in woodcraft but my uncle is. My father and I gave him a large slab of walnut cut from trees at my childhood home, and he's agreed to make me some wood for my Expobar Office Lever. I have a few questions I hope you guys can help me with. So many of you are experts and have made beautiful wood parts for your machines!

I'm looking at getting him to make the following parts:
3 portafilter handles
3 "joystick" knobs
2 steam/water knobs
4 feet
1 tamper handle
(and a partridge in a pear tree! )

Here are my questions...
Does anyone know where to get square hole bushings for the steam/water knobs?
It looks like the brew lever knob is M8; is that correct?
What about the thread size of typical steam/water joysticks (I might switch to those at some point and I'd like to have the joystick knobs done)? Like the replacement ones that Chris sells here. Do I need to use a threaded insert in them or can I just tap the walnut directly?
Since wood is lighter than bakelite/rubber, do you guys usually make the wooden handles longer/larger than the stock plastic ones? What length/diameter do you suggest?
My uncle likes to turn wood but hates finishing, so I'm on my own for that. I've used spar varnish before, and I've used epoxy resins (for building composites). Can I brush or rub on something like Danish oil or Tung oil, or is it important that I use a vacuum to stabilize it into the wood?

Thank you guys sooo much for your help! Sorry to ask so many questions....

Here are my questions...
Does anyone know where to get square hole bushings for the steam/water knobs? (dont bother, use a chisel to cut the square hole and put a drop of thin compound CA in it to reinforce the wood)

It looks like the brew lever knob is M8; is that correct? (yes, walnut is soft so you will need a M8 insert for the wood)

What about the thread size of typical steam/water joysticks (I might switch to those at some point and I'd like to have the joystick knobs done)? Like the replacement ones that Chris sells here. Do I need to use a threaded insert in them or can I just tap the walnut directly? (same as the brew lever, M8 thread and you will need threaded inserts)

Since wood is lighter than bakelite/rubber, do you guys usually make the wooden handles longer/larger than the stock plastic ones? What length/diameter do you suggest? (what ever fits your hand and is pleasing to your eye)

My uncle likes to turn wood but hates finishing, so I'm on my own for that. I've used spar varnish before, and I've used epoxy resins (for building composites). Can I brush or rub on something like Danish oil or Tung oil, or is it important that I use a vacuum to stabilize it into the wood? (just dunk them in danish oil, if you want a hard finish use a catalyzed urethane. Spar, polly, etc will not take the heat and blister)

I have made a few sets.
Custom Wood for your Espresso Machine

Dave, thank you so very much for the reply. You are a master at this! I have watched every update in your thread for a long time...if I didn't have the sentimental attachment to the wood (and my uncle), I would be standing in the long line of folks anxiously awaiting their chance to own your woodcraft!

I'll post here what I end up with.