Built a new grill

Just put together a little dry stacked grill today. Fired it up and it works great. It was super cheap but i wonder if there’s some modifications i can make to increase the durability of it. As i understand it, cinder blocks don’t hold up well against flames. My neighbor gave me a hand stacking this and we turned the bottom blocks on their side to get some airflow under the fire. You can hear it make a bit of a whoosh sound which is cool and keeps the smoke down. I was was thinking a cheap mod could be to move the cinder blocks out a little bit and line the interior burn area with bricks. Any other cheap mods i can try?