Might be too much to ask of Jacob at 3, but what if he carried the rings down the aisle and then handed to ring off to josh/Megan/Katie?
Infinity Wooden Wedding Ring Box
Denim Burlap Lace & Pearl Rustic Wedding Bow
Rustic style Ring Bearer Box, an alternative to a Ring Bearer Pillow. This box holds both his and hers rings in separate compartments. This is an adorable way to present your rings. Makes for awesome