it's definitely possible - but is it a good idea? almost definitely not
starting out so constrained will lead to poor ergonomics, unrealised potential, overspending on cases and possibke disillusionment with modular synthesis
start bigger and reduce (if you feel you need to) once you know what you are doing, what modules you actually want an (more importantly) need and how you work in modular
there is no need to fill a large case with modules - that's what blind panels are for
a mantis is easily portable, by all but the smallest children...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities