Yes that paint job looks awesome on both. However, I will tell you that that is going to be pretty darn expensive and pretty fragile for the slingshot to use flake buster metallics!
Prep all the pieces, spray epoxy primer, spray candy base coat, spray the flakes with a flake buster gun, spray two coats of clear, let dry, wet sand, more clear, let dry, wet sand, more clear, more sanding. Final clear and then color sand and buff!
Whew.... I get tired just thinking about it!
There are many other options with flakes but give somewhat the same effect but are not as fragile.