I do the same because although they are cheap they are not good for the environment to keep throwing away so I try to reuse everything that I can including old plastic ejuice bottles or just buy glass ones now. I will have to get one of those bottle holder’s that you mentioned or a test tube rack.I've used the same 2 disposable plastic pipettes that came with my initial flavors for the last 3 years.
While mixing, I just run it under the faucet then shake it like a Polaroid picture. When done, I stick it in my brush holder on the windowsill pointed down. That's just me.