Dome
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That would be difficult to do by sheet thermoforming (vacuum or pressure forming).
Tall shapes with steep sides are difficult. The plastic solidifies where it touches the mold first, and the remaining plastic has to stretch the rest of the way. That results in exponential thinning for completely vertical sides like that.
Forming it into a female (concave) mold with plug assist would help. Plug assist pre-stretches the plastic down into the mold before sucking it mostly outward onto the mold, and results in a more even plastic distribution. Still, the vertical sides would be tricky, and if you need nice optical properties---that looks like a clear display dome, where you would---it's that much harder.
Blow molding (like for soda bottles) might be good enough, but maybe somebody more knowledgeable than me about such things should comment.
(How are plastic bell-jar-type things usually made? Are the cast, blown, or injection-molded, or what?)
I'd look hard for an off-the-shelf product with the right dimensions, or something too tall that could be cut down to size. It's a pretty standard shape, so I wouldn't be surprised if there's something you could just buy.
