Desperate Times: Alien Bike cave - Building the cave

This is a project that I am working on. It is for Desperate Times: Part 2.
It is used by an alien species to dock their speeder bikes (alien and bike shown in earlier posts). This post is trying to get the initial shape of the cave.
If you want to join Desperate times, it is in the Roleplay and fanfiction section of the forums.
Hope you guys like this!