I engineered a downspout with a side hole to divert water; however I also need to cap off the bottom of the existing 2"x3" orginal downspout. I can't find any "caps" anywhere so they might not exist. Does anyone know if the downspout caps are available to purchase anywhere? Thanks!

I engineered a downspout with a side hole to divert water. However, I also need to cap off the bottom of the existing 2"x3" original downspout. 

I can't find any "caps" anywhere so they might not exist. Is there a way to cap off the downspout?