Hi there, welcome
It’s great that you are looking for ways to improve his happiness and well being. He does sound like he is bored and wants more room to exercise. Could you potentially bunny-proof your room, and allow him some supervised free-roam time for a few hours a day? Usually a couple hours morning and evening makes a huge difference (they can run their bunny 500s and burn off energy).
Do you have any toys for him in his pen? There are some great DIY cheap things you can make as “boredom busters” that he might like (if you check out the Bunny Info tab at the top, there is a section on toys and boredom busters). Things to dig at and shred are often very popular with active buns. Phone books, paper towel tubes stuffed with hay, cardboard boxes stuffed with paper and holes cut in the sides, and similar things are all very good for active bunnies!
Another thing to consider might be building him a condo within his pen, where you build up. This would give him more square feet to explore, and adds interest as well. I have a 4 level storage cube grid condo for my buns, then they get supervised free roam while we’re home. They like spending time in their condo, even when the doors are open and they have room to run around (I think they think of it as their burrow). My apartment is small though, so their free-roam time is still only in a large room. I think as long as the space is big enough for them to get up to a full speed run, they are pretty happy.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.