Some type of in-game timer. (as sharing Ender timer config files is a bitch.)
Size:
- Small. (similar to a dream-catcher)
Object options:
- Just set it, when the time is locked with the object. (Cheap to build. Time needs to be set/branded before it can be used.)
- A manual reset(to off) option perhaps.
- Option to set a new count-down time. (More expensive to build)
- (forgot) Some short label option would probably be useful here to. (the write one's type I imagine)
Object States:
- Minimal 2. (On/Off)
- But a bit more might be nice to.
Resource Costs:
- Sand of course. (Definitely for its build. But It could also use sand for it to operate. Giving sand at least some more use.)
- Glass perhaps to. (Which might also be needed to fix it when broken.)
- (Other general build materials)
Needed Skill:
- Time keeping.

Think that's basically it.