What should I make?

It has come to that time when I can start working on a project. I have a lot of things that I want to do, but  only have time for one.

Options

- Improved bullpup with a writeup

- Expanded hornet tank with homemade shell (mostly pvc and some polycarb)

- UMB tank in a Longstrike or Firefly

- UMB tank and expanded hornet tank in a Longstrike or Firefly

- Crossbow overhaul

Which one should I do? Please let me know in the comments because I can't decide.