Best way to store a cart

I have a Koetsu Rosewood Sig that I want to put into long term storage. The cart has been recently rebuilt so I would like to protect it from the elements as much as I can.

I am thinking of perhaps vacuum sealing it? Would that help?

Liquid nitrogen?

Vacuum sealed in a cool, dark place.

My two cents worth.
No liquid nitrogen. You don't want to harden the rubber suspension.
I would say add a dessicant pack before you vacuum seal it.
Paul, if you are really concerned about protecting this fine cartridge from the elements you will, undoubtedly, want to store it at my house. Feel free to contact me directly for the address.
A glass jar with a tight fitting metal lid and a single sachet of commercial oxygen absorber such as AGELESStm.

These are easily available through your local [strike]paranoid fantasist[/strike] "survivalist" supplier.
doesn't dry air harden the suspension over time? I was told to store them in moise air instead. you rather have mold which will not affect sound than hardened suspension?
Semi, Oxygen is a reactive gas. It and Ozone (O3) are what causes rubber to harden and degrade. If it is removed from the container, the atmosphere is inert and no oxididative degeneration can occur.
Thanks for the ideas. The oxygen absorber & glass jar sounds like a great idea.

Glad you like it.

BTW the reason for specifying glass and metal is that most polymers are highly permeable to oxygen. The exceptions (such as PVDC (Saran) and EVOH) can be hard to find.