These are some of the handy things that every fettler should have. I'm not saying aquire the same things I have, but these are some of the things that I use regularly when I'm doing things.
Driver Set & Bits
When you're opening & closing small fasteners you want a decent set of bits with a good selection of phillips, flats, torx, security etc. This is the iFixit something or other. It comes with a whole bunch of bits including some nut drivers and some fairly obscure security bits. The handle is aluminum with a magnetic bit holder. It's got a nicely knurled grippy bit, has a lovely smooth end with a bearing inside for silky smooth driving. There's even a flexy bit for those hard to reach places.
iFixit bit set with a small driver handle.
It all fits in a foam lined case with magnetic closure to make sure you keep everything together, and it doesn't open and spill it's guts when you stick it in a bag for mobile jobs.
Of course it's got a label.I've got a small one and a large one mounted under my desk on a pair of 3d printed brackets.
Calculator
If you're a maths genius, then you probably don't need a calculator. I'm not a maths genius so having a calculator is a must. I've had this one for a while, since sometime in 2014, I bought it when I was studying for my intermediate ham licence. It's a belter. You don't need one like this, but this is the one I use.
My stonking HP 35s.
This particular calculator lets you use RPN (Reverse Polish Notation) for calculation entry. https://en.wikipedia.org/wiki/Reverse_Polish_notation it's perfect to stop it going wallkies from your desk, unless you know how to input in RPN the calculator doesn't work! If someone borrows it, it comes straight back.
The buttons on this are a good size and require a proper press to activate them. It's simple to use and packed with features. The screen is only 2 lines but the digits are clear and bright. The only annoying thing about the calc is the reflective screen glass, aside from that, it's perfect for me.
The pleather sheath keeps it nice when you're not using it.
The sheath slips over the calculator when it's not in use and stops it getting battle hardened in your bag. There's rails on the edges that stop buttons gettid pressed in your bag too. Mine is at least 10 years old and still looks box fresh. It fairly motors through batteries, but they're cheap and easy to get hold of (CR2032).
Cutters & Pliers
Flush Cutters, Needle Nose Pliers & Screw Pliers.
You want some sharp well finished small flush cutters. They chew through thin wire nicely and leave zip ties skin safe, the guy who comes after you (probably you) will thank you when a nicely flush cut zip tie end doesn't slice his/her hand open and make him/her leak blood everywhere. They're perfect for trimming the legs of through hole components and don't leave knife like edges.
Needle nose pliers are always handy, grabbing lost screws, tightening small fasteners, clicking like castanets when you're deep in thought.
The third pair is a set of screw pliers. As well as the normal grips in the jaws, in the end faces they have vertical grooves that make removing rounded, stubborn screws a breeze. For that time you need them, they're a godsend.
Utility Knife
Utility knives.
Always handy to have a sharp cutter about on the 'healing bench' (C)AvE, they're useful for a million different things. I prefer one with a snapable blade so i've always got a sharp bit of blade ready and I don't feel too guilty using it for naught stuff like cutting antenna wire. In the garage I keep a 'Stanley' knife about. The amazon one is fine, if I'm doing nice cutting (nice cutting!) I like to use the posh one!
The blades come in a wide variety of widths, I've got a 9mm one, and 18mm one and a chonky 25mm one. The 9mm one is more of a stationary (as in paper) knife, the 18 & 25mm ones are for most everything else.
The Business End.
When the blade isn't as sharp as it was, you simply extend the break score to the edge of the knife body and bend the blade against your bench/desk until it snaps off. Probably best if you put your hand or a rag over it to stop it pinging off into the distance. Even though they're not as sharp as when they're box fresh, it'll still give you a decent cut when you find it at a point in the future when you weren't looking for it.
Olfa blades are the best in the business.
The Amazon one get's Amazon blades, but the posh one gets posh blades. The posh one was a kit from AvE (YouTube). It's laser cut stainless steel layers with a titanium blade guide (just because). It weighs about 5kg and in a pinch can stand in as a hammer, crow bar or other piece of demolition equipment. Building it was one of those really satisfying projects, and as a knife, it's a joy to operate.
Multimeter
Digital Multimeter.
You need a multimeter to help when fault finding. It doesn't need to be a Fluke one, any meter that does, voltage, current & continuity is all you really need for dad level fault finding. Sure if you're an engineer working on complex equipment in a critical industry get a calibrated £3,000 beast. But if you're just following voltages, looking at current draw & checking for continuity an aliexpress special will do you just fine. As long as the screen is clear you're golden.
Modern meters all do the three basics and unless you really know what you're doing you probably don't need anything else. If you know what you're doing, why are you reading this page? If the meter does auto ranging, that's handy and if it reads temperatures via a thermocouple, that's also handy.
Aliexpress Digital Multimeter.
I've got a few meters. The nice (relative term) Tenma one that came from CPC and the Aneng aliexpress one live on the healing bench (c) AvE. There's another aliexpress special in the garage and one in my RC bag.
It's handy to have a few different probes to go with them, you want some standard pointy ones, some pointy pointy ones and some clip on ones. With them there should be nothing you can't measure, no dodgy thing you can't locate or busted trace you can't hunt down.
USB Tester(s)
Aliexpress USB Testers.
Couple of USB testers are handy things, put it between the thing you want to test and a battery, you'll see if the device is drawing any power. The white one is an older one with no USB C. The black one is a new whizzy one with USB C and all kinds of information on the screens.
They're both from aliexpress so were cheap as chips. They're probably not the most accurate things in the world, but for dad fixing, they're perfect. The video below shows the different pages. A cool thing I like is that it's got a sensor in it, so if you hold it in portrait the screen flips.
Unfortunately neither do Mini USB, but an adaptor solves that. The white one does USB A & Micro USB. The Black one does USB A, USB C and Micro USB. The black one also does USB PD testing too.
Connectivity on the FNIRSI tester.
Battery Chargers
Back in the day, rechargable batteries were a compromise, but as battery technology has advanced, the tables have turned. New cell chemistry & smart chargers mean that unless I'm desperate, it's rechargable all the way for me.
Xtar VC4SL LiPo Charger.
Most of my high power devices (torches) take 18650 cells, most of the cells are Samsung or Molicel, I get most of them from Fogstar batteries.
The charger is an Xtar VC4SL, it charges 4 x 18650 cells and has a USB C power input. Depending on the oomph of your USB power supply it'll charge a single cell at upto 3A, 2 cells at upto 2A and 4 cells at upto 1A. As well as charging it measures internal cell resistance and provides capacity information. It's got all the usual protections; polarity, over charge, temperature & dead short. I've had this charger since Jan 2022, replacing a dead one and it's a fine example of a charger!
For everything else (AAs & AAAs) I mostly use Amazon basics cells. They're cheap most of the time and cheap as chips when they're on sale. I charge them with a Youshiko smart charger.
Youshiko YC4000 Smart Charger.
The charger has a 12v wall adaptor. It'll charge at upto 1A. As well as charge, it does discharge, cell refresh (charge & discharge cycles) and capacity tests. It has all the protections you'd expect; polarity, over charge, temperature & dead short. I've had this since Dec 2015, replacing an old 7dayshop one (which I still have for some reason!).