ideas for creating linear movement/ general suggestions for approach please

thx,

but idk about that pair of bellows, how to "drive" it and about its "fixed" volume with its flexible parts.

so far id think zoomkats suggestion link and AWOLS leadscrew r the best suggestions i could implement.

I painted what i think would work, is that what awol was talking about with his leadscrew?

I have problems finding those parts on ebay, what i call threads is that a leadscrew?
What i call screw, how would you call that? It needs to be bigger then a regular screw as i have to attach somehow that syringe.

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