A method of designing the vacuum chamber for multiple-layer ion mobility cyclotron devices at the elevated pressure includes an airtight chamber body with end members for ports including the interfaces to the ion source, the noble gas inlet and outlet, the electrical feedthroughs, and a mass analyzer. The chamber has a pair of openings for end members which can be a blank cover or another chamber body to extend the layers of the cyclotron devices. The chambers are arranged to be stackable using bolts and brackets around the chamber to maintain stable structure. The bolts also press and tighten the sealing members which are disposed along the joint surfaces.