You do not want to handle them right after they eclose. Give them at least a week and a half to two weeks to mature and become active then proceed to handle them.
I agree with Beetle-Experience on the dimension of the chambers. I'd like to add that you can also use wet paper towels, peat pots, and wet toilet paper roll to construct artificial pupal chambers.
I made mine vertically since Japanese rhinos are known to construct vertical pupal chambers. Your chambers appear to be a little bit too wide so if I were you I'd make them vertically without being too wide. I would upload a picture of mine but I threw the foam away after they eclosed due to molds.
Just make sure the females have completed their pupal chambers and have lost mobility or they will construct a new pupal chamber once you've destroyed the original ones, or they will crawl around and even out of the artificial pupal chambers.
What do you guys think about intraspecific hybridization between Allomyrina dichotoma septentrionalis and Allomyrina dichotoma tunobosonis? I know hybridization may produce sterile offspring but I want to know what you guys think.