Very nice craftsmanship! I'm quite impressed.

Don't worry about him staying in the log. Ball pythons love the security of cramming themselves into dark, tight spaces.

It's a bit odd to have a heat pad on one side and a heat lamp on the other, though. I'd move that lamp over to the Left-Center of the cage, so that your enclosure has a distinct temperature gradient with a clear "warm-side / basking area" around 85 - 90 degrees and "cool side" around 75 - 80.

Also, if you're not using one, I'd get a hold of a thermostat to control your heating devices.