Cut a 4" length of the wooden dowel by scoring it with your knife and snapping it with your fingers. File off an rough ends or edges.
Check to make sure the wooden dowel fits through the eye screws and can spin freely. Too loose is okay, too tight is not. If it's too tight, use your file or some sandpaper to remove some material.
Insert the wooden dowel into one of the laser cut wheels. It should be snug. If it’s too loose, wrap the dowel in a little duct tape and try inserting it again. If it’s too big, use the file to sand down the end until it fits.
Then feed the dowel through the two eye screws and attach the other wheel.