About 25 years ago i built a greenhouse using double glazing panels i bought 35 panels @£2 each 70 sheets of glass the panels were 3 ft by 3ft 6 inches ideal for the job in hand ( i only use imperial measure dont get mixed up that way)the wood was perchased from a second hand wood place for £ 22. and a lot of work but it is still standing so i did something right .
To split the panels i used a hacksaw across the corners once i got a road in i used a jigsaw a bit tricky but with care possible so things can be done with double glazing panels .
The Greenhouse finished up 19 feet long 10 feet wide and 10 foot to the ridge Jacob