Go to eBay.

Search for “spares or repair.”

…

Profit?

If you just understood and could fix problems with DPFs – even for just one make / model –  to the extent that you could tell a customer whats actually wrong (ie whether the DPF itself is the culprit or the victim of something else)  and what you’ll do and what it’ll cost  to make it better…… then thats a niche service right there.

So rather than working speculatively buying, restoring, selling perhaps look at something with a known Achilles heal that makes that ‘thing’ much more economically viable with your repair/ modification.

This is the best advice if you want to go the automotive route. Another example that was doing the rounds a few years ago was Vario seazed injectors.

I have been racking my brains for years for something similar. My CAD is shit but otherwise I have been fixing everything for years in work and at home. Out of touch with cars now due to a long period with no workshop

Back on topic, the best repair niches are industrial ime. The cost of the plant is massive but more to the point the cost of the plant not running is the real cost! The difficulty is finding the niche as you t nd to need to be in the industry. One thing I would consider is getting into hydraulic repairs. If start off man with van doing hoses etc you can then get known for doing more. The issue is if you then start doing cylinder repair the size and weight can require some good workshop space even if you get the cylinder off on site.

Other area is if your bold work has lots of machines in the field if you can set up as a indipendant field service engineer / machine modifier. This would upset your employer possibly but they may have clients they don’t want to deal with as they are too small fry / not profitable for a “proper” business

For variety – repairs / restoration for industrial or science museums – or the production side of interactive exhibits

I produce graphic panels for local museums/exhibitions etc and as one of my hobbies is Raspberry Pis I always try to interest people in some kind of interactive display! No-ones bitten yet though, I think they think it’ll be too complex/take too long/cost too much (probably right on the last point, neither local museums nor exhibition work seems to have much budget these days!!)

I do have a customer though who produce events for corporate clients, they have a guy full time who’s a chippy/fabricator/electronics/programming guru who builds stuff – sounds very fun & varied and these kinds of customers do have a reasonable budget. Examples of what they’ve done include chopping the front off a car and making a “whack-a-mole” game where the engine was, an interactive VR halloween horror thing for Fanta set in a lift, and intentionally crashing a car so it resembled the one from the tv show “End of the **** World” 😂

What about old style radios (50/60s bakelite style) with modern bits inside to turn it into an internet based radio? Retro stuff is fashionable, apparently, so people will pay silly prices.

Not sure how to quote now, but I know OP said audio doesn’t excite, but met a chap the other day making a tonne on buying spare/repair vintage amps and retro modding modern gubbins for bluetooth etc. Really cool stuff.

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I was in a piano shop the other day.

It was full of £40,000 pianos. Lots had been refurbished.

Piano refurbishment?

£40k piano delivery expert?

How about smart home technology. Entry level is a change to full led lamps, for alot of people this is beyond them.

Then smart heating, smart security, smart music.

If not then bespoke fabrication. Glass and stainless staircases for example. Pagodas are big darn south at the moment.

You need to tap into the wealthy and supply what they want

Turntables inside their garage, pointless to you and me, but if you own 8 cars and have a convert ed stabled this is where its at.

Race car build? Specifically classic stuff. Mult millionaires dont race their lambo at goodwood, its a copy.  Look at historic sporys saloons, buy old capri and make them into zakspeed replica, or any ford escort mk 1 or 2. People pay bonkers cash for turnkey race cars

I think both maccruiskeen and zilog are onto something with museums and theatres; exhibitions less so but that’s only a personal view based on absolutely no direct experience.

Handyman on a country estate?

You need to tap into the wealthy and supply what they want

A sound engineer who used to Freelance for us has turned his car audio] obsession into a full time business and has had to take someone on. One client has just flown him and his wife to Australia to work on his car! He was going to ship the car to the UK but decided it would be quicker to fly him out. Obviously not short of money.

Retrofitting something that looks like flames to the soon to be defunct log burners.

I always fancied the idea of fixing coffee/espresso/bean grinding/barista machines

In which case, I have your answer OP.

You are basically this bloke:  http://coffeemachinist.com.au/

Who also does a lot of work for these blokes (who are being extraordinary successful at the moment):  https://spechtdesign.com.au/

Also consider this bloke:  https://www.kafatek.com/

These two are interesting also:  https://newtonespresso.co.nz/ and http://www.cafelat.com/robot.html

All of whom seem to do alright with basically a shed-based business doing exactly what you describe.  I particularly like the Kafatek model:  he does a production run every quarter – you pay a deposit (which I assume covers the outsourced manufacturing of the components, which he then assembles and ships after final payment.  My back of a napkin calculations has him doing very well out of it, with a business that he can scale up/down as he wishes.

The world of specialty coffee loves boujie products like these.  If you are in any doubt, check out the “accessories” that Weber workshops sell.  Fairly sure you could knock-up some of their “bean cellar” line up without too much difficulty and turn a profit.  (https://weberworkshops.com/collections/coffee-accessories)

A sound engineer who used to Freelance for us has turned his car audio] obsession into a full time business and has had to take someone on. One client has just flown him and his wife to Australia to work on his car! He was going to ship the car to the UK but decided it would be quicker to fly him out. Obviously not short of money.

I know a guy in Sydney who does something similar but in houses. Basically building bespoke AV systems in the houses of people we’ve heard of in the media. It’s a bit sad actually as he’s personally over the whole consumerist lifestyle whilst being dependent on it to feed his family. But he makes a fair bit of coin.

You obviously have a significant talent.  I think you might have overlooked @jaminb suggestion.   New lithium batteries on boats and motor homes, not for propulsion.   I know 2 people looking for this now, high value specialist work.

Thanks for the input / suggestions / links etc, I’ve got the XC90 to finish before I can do anything else and I’m just taking the money and running now as far as work is concerned but I will do something soon(ish).

I’ve just finished adding a self designed and built 40bar liquid CO2 blending system to this mixer so the links to coffee machine’s above and their talk of pressures piques my interest even further!

My Porsche?

Business converting Euro 5 to Euro 6 diesels. Lots of very usable low mileage Euro5 cars and vans about that could be converted so they can be used in the various LEZ cities.

Also converting Ice cream vans to run on batteries. They love keeping the old 70’s vans on the road but would benefit from not running everything on the diesel engine all day.

ive thought about stuff like this. basically you want to look into a market that has a lot of people with disposable income and/or a need.

ebikes fall into that category and it would be very easy to set yourself up as a motor repair specialist.

What ever you do, make sure you start a YouTube channel.

This Guy

https://www.youtube.com/@M539Restorations

Was in IT with a passion for old BMW’s, he now restores BMW as his day job for YouTube, mostly keeps them, sells some, as he feels like it.

I don’t know of anyone doing it for Volvo’s?

Dunno about Volvos, I do know I guy who now does his hobby full time to earn a living which is restoring Morris Minors. Absolutely massive demand apparently, always has multiple on the go & the owners are not shy of spending money!

Removing, refurbishing (or converting), and reselling Agas and other range cookers.

You can’t give them away and to buy a refurbished one costs many thousands.

What ever you do, make sure you start a YouTube channel.

I do need to start a channel as our XC90 has a good back story. I paid £500 for it as that’s what the owner friend was offered trade in value, I’m looking to spend ~£3k on parts plus a bit of CAD time making it into an ‘Overlander-lite’ then we are planning on driving it to Sweden so we can visit the Volvo museum and then on to Finland so Bert our Karelian Bear Dog can visit ‘home’

Move to an island in Scotland and build a distillery?

Go to eBay.

Search for “spares or repair.”

…

Profit?

Based on the electronics repairs stuff I’ve watched on YT I think the last bit is hard.  I’ve been surprised at the prices broken stuff goes for, not leaving much margin, and there’ll be a natural skew towards hard/uneconomic repairs in listings because people may have already tried a local repair place before listing, or may be other repairers chucking stuff back on ebay after failing to fix.

I think repairing car electronics is a good shout.  I shipped the sat nav from my old BMW to Poland for repair for £150 or so.  The repair probably cost pence in parts, but this was still good value compared to sourcing a replacement.  Similar story with fixing something in the instrument cluster in my mum’s car.

Whatever you’re doing I think being profitable means doing exactly the same repair, again and again, so you probably don’t get the satisfaction of problem solving that you do when fixing whatever random stuff comes your way.

I think the winning plan is making a living from YouTubing yourself unprofitably fixing random, interesting stuff.

It’s an interesting topic. With the fact all the easy money is beasted by everyman and his dogs uncle before you have even thought about it. The way corporate companies sew things up, with patented interfaces/connections, who they will and won’t supply parts to, as well as parts they won’t supply to anyone at any price!