Tooling maybe, but I wouldn't underestimate the required know-how. For example, making good vacuum-grade glass-to-metal seals is a technology that took decades of research and experimentation.
also, fusion (not online, but available in many university libraries) is the quarterly journal of the american scientific glassblowers society https://asgs-glass.org/fusion-journal-asgs/ and they also have had symposia which have published proceedings (not online)
and it's common for scientific papers from the period when this stuff was getting figured out to describe their apparatus in detail (rather than saying they purchased such-and-such a model from such-and-such a company), and those are online
finally, the bell jar seems to be defunct, but they have put their 27 issues online https://www.belljar.net/articles.html
Or you can take up glass blowing! This is, in principle, 125-year-old technology, and therefore possible to construct with non-esoteric tooling.