Continue to travel through the unblocked parts of the cave until you come across your first Puffbird! Its so cute...

Time to Kill it.

Unfortunately to craft the nomad pistol you will need 10 Carbon, which can be easily obtained by smacking around some Puffbirds. Once you have collected the necessary Carbon return to your ship and use the 3D printer to create your Nomad Pistol

Now that you have the pistol you can return to those purple crystals and break them, giving you a way out of the cave and the opportunity to continue to explore the planet.