A circular saw is awfully good to have (both for coop building, and in life in general).
You don't actually NEED one to build a coop (especially if it is designed to require no cutting-to-size of plywood) -- you CAN use just a good aggressive-toothed handsaw (something with 9-10 teeth per inch is about right), and yes you CAN cut plywood that way -- but spending $35 on a basic circular saw is a good investment and will save a fair bit of sweat.
The abovementioned type of handsaw is still very useful to have, of course, for times when you're only making a coupla cuts and it isn't worth setting up the circular saw!
Other than that, you've already got everything you need
Go for it
Good luck, have fun,
Pat
You don't actually NEED one to build a coop (especially if it is designed to require no cutting-to-size of plywood) -- you CAN use just a good aggressive-toothed handsaw (something with 9-10 teeth per inch is about right), and yes you CAN cut plywood that way -- but spending $35 on a basic circular saw is a good investment and will save a fair bit of sweat.
The abovementioned type of handsaw is still very useful to have, of course, for times when you're only making a coupla cuts and it isn't worth setting up the circular saw!
Other than that, you've already got everything you need

Go for it

Good luck, have fun,
Pat