Click a picture to see a larger view.
Aproximate size: 8 foot 6 inches port-starboard; 6 foot 3 inches
long aft to bow.
Aft risers are 2 foot six inches.
Any good boat canvas shop can put one of these together but
source has a good reputation.
Also, if you want to see what other boaters have done search the
sailboatowners.com archives. Then type in the search term "bimini"