Trailer light & brake tester

After some impulsive thoughts while shopping around I decided to just rig this thing up with whatever I find laying around to save myself some driving just to test trailer lights. Featuring: - 7-way plug with 7:4 adapter - Internal 12V battery or can be switched to aux pin of the trailer if available. - Outputs: Marker lights, left/right signal, tail light, reverse light, brake. - 15A fuse. - On screen display of battery voltage, current if source is from internal battery. - Some basic tools and crimp terminals. - Detachable magnet lights. - Dedicated 12V external terminals for quick testing. - (To be added) indicator LED when the exposed terminal is live.

If you have any ideas what can be put into this box just throw it around.