The phrase "assembling inside" is correct and usable in written English.
It can be used to describe the action of gathering or putting together components or elements within a specific location or context.
Example: "The team is assembling inside the conference room to discuss the project details."
Alternatives: "gathering within" or "putting together inside".
The furniture had to be constructed off site and then assembled inside.
Night fell, and the family assembled inside for a dinner of tomato-and-eggplant casserole and to toast another harvest.
Many of the students who dug this fall will assemble inside for a spring term laboratory course, where they will clean, examine, research, and catalog their finds.
He imagined a swarm of his antiwar brethren: "If the image is of the President and Republicans assembled inside, having a strong, united, purposeful Convention, and you've got a bunch of ragtag, you know, anarchists and leftists and long-haired demonstrators and foulmouthed accusers outside, well, the contrast — I can tell you who will win that one".
With all due respect to Harvard, its neo-Georgian brick neighbor to the north, the Stata Center may be one of the smartest buildings on the planet, not just for its computer-assisted design, but also for the minds assembled inside.
As they watch, the Planet People assembled inside the circle are bathed in a bright light and disappear, leaving only a residue of white dust.
This went on for several hours, interrupted a handful of times by protest chants and angry New Yorkers hordes had assembled inside and outside of City Hall.
The most straightforward interpretation of these data is that such phases also assemble inside authentic NPCs and account for the permselectivity of nuclear pores, as previously predicted by the selective phase model.
A manageable 50 guests were assembled inside.
Cameras, reporters and a podium were already assembled inside.
