So as to not just be a miserable old sod, let's look at the new prop toys which are presumably (like the DIY Sonic screwdrivers) not actually going to be in the show. what could one do with them?
The Trans Temporal Sonic Screwdriver
is, well, a sonic screwdriver. In this case it's intended to blend in with 19th Century Europe, looking like it was cobbled together from bits of a Victorian bathroom suite. So perhaps it's an emergency replacement for a traveller stuck in the time.
The Dalek/Cyberman Anti-Time Device
"Use scavenged Dalek and Cyberman technology to wipe your enemies from time!" That doesn't sound like something the Doctor would approve of, not without offering them a chance to give up at least. So maybe it's in the hands of a survivor of a terrible Cyber-Dalek-Human war, fighting to stop it ever happening.
The App-Gear Blaster
Rebuilt without the Dalek eyestalk, making it a bit smaller, perhaps intended for a stealth operation. The designers have added a cradle for "leading smartphones" which connects to the alien device to let the carrier detect and target otherwise invisible aliens. It appears a Secret Invasion is afoot!
The Personal TARDIS
"Set the Time Coordinates, flip up the Time Rotor, then prepare for time travel!"
Most mysterious and powerful of all, a TARDIS worn on the arm, clearly salvaged from various sources including an 80s home computer, perhaps based around a rebuilt Vortex Manipulator? Compatible with the Trans Temporal Sonic, so very possibly the creation of the same stranded traveller trying to force his way home.
So who created these things? A brilliant technician, obviously, on a desperate mission across space and time.