H26/260 Bimini
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 this 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"