screen enclosure for young
I also have a 3 month old Panther Cham. When we got him just a little while ago we put him straight into a screen enclosure and he has done great in there. He moves around a lot and doesn't have any problem finding the crickets and fruitflies we put in there. We did encounter a few problems though, so I will let you in on those...
First of all, the baby crickets you have to feed to your young chameleon are masters at finding every hole in your cage to escape out of. It is really uncanny. So we had to do a lot of plugging up of seams, etc. But since you have a reptarium it will be different from my aluminum cage.
Second of all, like you mentioned in your worry, I saw one day, Python, my chameleon, decided to suddenly race up his cage to the ceiling and started going straight for the heat lamp. This was pretty soon after we got him. So I stuck my hand in there to have him climb on it and not go under the lamp, but he got pretty freaked out and ran away. I took my hand out of the cage and immediately he was up to the same thing again. So what we did to solve this was to put 4 inch thick layers of tape all around the light (we used mailing tape). Now by this I mean we taped the inside of the cage with flat strips about 3 inches away from the light. Since then, he has tried to do the same thing, but cannot get to the light because the tape is slippery and offers no grip, so he doesn't try and venture any further. So then he just goes to his basking branch instead. That has worked for us, I don't know if any experienced cham owners would object to that type of setup, but I would recommend it. Definitely move him to the screen enclosure though, he is plenty old enough.
Quick question for you, is your chameleon friendly with you? I am still working on building trust with my chameleon so he will even let me go near him. He is still really scared of me, though I have been doing everything I can to be non-threatening.
Rachel