It's claimed that the burglars smashed a hole in the wall and crawled in to JGR Auto Care in Wallows Road, Brierley Hill.
The garage had only been open for just a few weeks when it was targeted between the evening of Sunday, May 1, and the morning of Monday, May 2.
A pre-existing hole in the brick wall had been widened, with owner James Russell believing it was smashed open with a sledgehammer until a hole became big enough for someone to crawl through.
Mr Russell said: "I can't really explain it. It's just gutting. It broke me a little bit, to be honest with you."
The 29-year-old from Rowley Regis believes a group of thieves scouted out the property, thinking there would be money and car keys on the premises alongside expensive tools.
Although James does not keep money or car keys in his garage overnight, he estimates that between £25,000 and £30,000's worth of tools were taken during the burglary.
James said: "I broke down a little bit, to be honest, because it's 15 years of my career basically.
"You don't just buy all these tools in one go, it's over 15 years. They've stolen some tools that were the first tools I ever bought, which is gutting really, it broke my heart.
"I started this journey of a new career when I was 17 or 18, going into this scary world of being mechanic and finally getting something to be proud of, and they've stolen it."
Stolen tools include thermal imagers, borescopes, ratchets, wrenches, and spanners - which James has always collected.
"And they took every single last one of them," he added.
A smoke machine was also taken, worth an estimated £2,000.
The mechanic said: "Not every garage has one but I try and pride myself on being able to offer services which other garages don't, so I do spend a lot on tools so I can do that.
"I would have rather them come in and stole money from me, I'd much rather that because money's replaceable.
"These are the tools I was buying when I was 16 or 17, just starting out, that's the most heart-hurting thing because those tools are irreplaceable."
James was so distraught he considered walking away from his dream altogether.
The mechanic added: "I really had to consider what I wanted to do, whether I wanted to go forward or just give it up and go back to working for someone, or just come out of the trade altogether.
"I do have quite a passion for working on cars, so I am going to stick to it.
"Obviously I've put security cameras in place, I've got cameras linked to the Wi-Fi so it goes to my phone, I've got alarms, and I've reinforced the walls as well.
"I've come to terms that I'm probably not going to get my stuff back, but I'll be staying, because it's the only thing I know."
James hopes that other garages will hear about his ordeal and be vigilant with their own businesses.
He said: "Other garages that have probably been here longer than me, but think we'll be alright, obviously it happens to everyone.
"Even if one person sees this and thinks, you know what, I'm going to put a decent set of cameras up that stop someone from doing that, then it's worth it."
A spokesperson for West Midlands Police said: "We were called following a break-in at a unit on Wallows Road, Brockmoor, sometime between 4pm on Sunday and 10.45am on Monday.
"Anyone with information can contact us via Live Chat on our west-midlands.police.uk website and quote 20/401293/21."