There are many ways to protect your ceiling and walls in a golf simulator. One of the most common methods involves using foam panels that do a good job absorbing the impact of flying golf balls. I strongly recommend giving these a look to see what you think, as they’re affordable, work well, and can last a long time even if you golf frequently. Another popular option is netting. Depending on the type, netting can prove more challenging to set up than foam panels. Still, it works amazingly well and keeps you from having to add anything to the walls. The only real difficulty behind setting up netting is ensuring it is strong enough to absorb head-on hits from golf balls if you swing directly at it. However, the process is not too tricky, and I find it well worth what time and effort it takes to get it right so your walls and ceiling are safe.