Bridge crane 2 ton

Looking to make a 2 ton bridge crane in my shop. 40 feet long. 20 feet wide. Need to know what size I beam for the 40 foot runners supported both ends and middle. And double square tube or I beam for 20 foot wide bridge. I have the trolley sections for the runners already. Rated at 4 tons.
Sterzinger’s welding llc.
Thank you Rich.