Pi-tastic
Ever since mini-biscuit started insisting on farting around with our garage door opener keyfob every time he got his sticky little fingers on it, I got really tired of always having to trot down to the basement to see if he'd managed to leave it open or not.

One Raspberry Pi, a couple of magnet sensors, a relay board, a bit of woodwork and a wee bit of coding later and I can see if the bloody thing is up or down from anywhere in the world. I even wrote a webpage especially for mini-biscuit that just contains a massive button the size of the full screen so even he can fumble around and eventually manage to press the button to open it for me.

Even better than that, was writing an app so that my telephone periodically works out if it has a bluetooth connection to the car, and if it does then it reports its location back to the Pi every so often - the upshot is that the Pi knows where the car is, and so as soon as I turn onto our street it opens the door up and I don't have to lift a finger any more and can instead concentrate on sweeping majestically in like a smug wanker.

Magic. Now don't you nice people go trying to hack it, now will you...

imgur.com/a/Gd54E
(airbiscuit last dropped a meaty one in the lift on, Fri 5 Aug 2016, 14:39, 11 replies)

Blimey, one I can answer
I bugger about with old motorbikes for a hobby. This usually involves improving them so they actually go and stop reliably.

First one I'll link to is my BSA Bantam:

1.bp.blogspot.com/-0wwKDcWfwfQ/UvgTzpEjg3I/AAAAAAAAAV4/czYxS9Xe-Uw/s1600/DSCN4539.JPG

oldnailsandswarf.blogspot.co.uk/2014/01/improving-bsa-bantam-heavyweight-forks.html

oldnailsandswarf.blogspot.co.uk/2014/01/bantam-improving-part-two-contains.html

oldnailsandswarf.blogspot.co.uk/2014/02/bantam-part-3-blundersprint.html

oldnailsandswarf.blogspot.co.uk/2014/07/bantam-improvements-conclusion-for-now.html
( Greenbat, Tue 2 Aug 2016, 9:58, 1 reply)

a few years ago
My Compact digi camera zoom lens got jammed by some sand. In an effort to DIY fix it myself, I decided to take it apart, give it a clean int he hope of learning how they work, and fixing it in the process. I was being very careful along the way to keep inserting the battery, to make sure the circuitry all still worked etc.

I was in the middle of assembling it back up when my dad/brother came up behind me and jabbed me in the ribs, the surprise of which made me throw the camera and its delicate contents at the ceiling and wall across the room. My body flipping out and wibbling off the chair i was sitting on. I laughed and yelped at the same.

I was furious. I turned around ready to shout when i realised there was no one there, and in fact it dawned on me that i had electrocuted myself.

My camera was in pieces, smashed to bits.

For such a small battery it gave quite a handsome kick.
(Dan dan dan They tik urh jerbs!!!, Fri 12 Aug 2016, 14:50, 7 replies)

There have been a few
I guess modifying things might have resulted from working in a windowless basement electronics repair workshop for too many years.

Memory vague but these stand out:
The addition of the beepy whistle key finder board inside the TV remote control. Never lost it again.
A cattle prod thing with paperclips that was made out of spare bits. Transformer was wound with a drill.
The sunburst wall clock that was turned into a toy robot with a wagging tongue called "Mr Licky".

Probably more
(Captain Ignorant what does this button do..., Tue 2 Aug 2016, 13:58, 2 replies)

i can't think of a single thing
I am beyond useless with any form of technology or common sense.

i'll just go for "i modified YM's arse with a massive black strap on" then.
( rachelswipe with a fork, Tue 2 Aug 2016, 10:08, 6 replies)

Swing set
When I was a kid, I removed the swings from the swing-set and attached a huge length of elastic I found onto each end of the frame. Voila, a giant slingshot that launched marbles very effectively.

I have no idea how far it actually shot marbles. Over the neighbor's and over the next street. How much further I never found out. I figured horizontal shots at the neighboring houses would be too easy to trace.
(xixax, Mon 1 Aug 2016, 12:27, Reply)

I bought an old Jag* last Christmas
the GPS was so old and ropey that it didn't have maps newer than 2010, so I butchered an old netbook and installed that instead.

5.1 surround sound (for front/rear/left/right zoning), bluetooth, wifi, phone screen mirroring, huge mp3 and film library, USB GPS module linked to the car's built-in aeriel, arduino-powered steering wheel controls, voice recognition, touchscreen, rear camera support and USB ports all over the place.

*it's just a posh Mondeo really.
( Grrrmachine the indifference engine, Mon 1 Aug 2016, 12:21, 8 replies)