With just one hull colour and the ability to freely select the hull colour in build mode I think would add to the game. Having to fiddle with many hull colours or save to buy the right hardened hull for the details you want adds very little to gameplay and stymies creativity.
Instead for gameplay, for those special build blocks that you would have to go through some gameplay to get, add a few more kinds of the ambient glow crystal blocks other than Ice crystals (and Lava). Examples; Jade (Light green), ruby (wine red), and Lapis Lazuli (Dark Blue with golden specks). I bet there are more crystal blocks people can come up with.
Instead for gameplay, for those special build blocks that you would have to go through some gameplay to get, add a few more kinds of the ambient glow crystal blocks other than Ice crystals (and Lava). Examples; Jade (Light green), ruby (wine red), and Lapis Lazuli (Dark Blue with golden specks). I bet there are more crystal blocks people can come up with.