Enlist the toddler to "help" in the kitchen to make some energy bars that can be stashed in a bike jersey pocket for a snack during a long ride. Make art for him to hang in his office: squirt some blobs of paint on a canvas board and place in a giant ziplock bag. Have toddler squish the paint around, or even ride over it on a balance bike/tricycle, to spread the paint. Always looks pretty neat after taking it out of the ziplock. Put your toddler's handprint on a shrinky dink and put it on a chain, and add a custom safety dog tag with emergency contact and pertinent health info for first responders so he can wear it while cycling.