Among others, both Curbell plastics/plexiglass; and Acrylite post extensive manuals online for forming their products.
Both indicate that for full 1/2 round free-blown forms, (height = 50% width) that apex thickness is less than 1/2 original sheet thickness.
Considering the article, annealing temp for Acrylite cast plastic is spec'd by the actual manufacturer as 175F. The length of anneal for .117thick sheet is 4.5 hrs followed by 2 hrs slow cool. Plexiglass is less specific, but various notes seem to indicate 175F & "slow cooling".
In the mid 70's i attended one of the original Monnett long weekend builder seminars for college credit and was exposed to the unit they used for blowing canopies for the -1 at the time. It was a somewhat insulated plywood box, with a length of black pipe in the bottom with a series of holes drilled for a gas or propane burner. So as noted in the article the equipment can be negligible.
More recently i have been studying the various manfacturer manuals as well as the old EAA builders reports (there are several on line in addition to the link posted by the OP) since it is necessary to blow an oversize canopy for my S2. As seen in the old reports, and as shown by several youtube videos, blowing a canopy does not seem to be a significant enterprise. A pizza oven could be used to heat the sheet, and if done promptly, blown in still open air. OTOH once the need for annnealing is considered, a more complex arrangement is suggested. I'm sidling toward a PID controlled insulated convection box built out of metal studs and sheet metal like all the similar temp powder coat ovens posted online, & have settled on some of the supplies, but not the configuration of the box. Heat differentials can be used to control thickness proportions to some extent as the bubble forms, or partial heated physical forms can be used, which is difficult in open air.
smt