This is an overview of how I made a kegerator.
It cost me around 600€ that includes the new fridge and 2 new kegs.

Materials:
1 fridge
1 sheet of plywood
6m trim
1m angle trim
.5l outdoor stain
.25l boat varnish
6m toungue and groove flooring
60cm 2x10
1 Tube silicone
Acrilyc
Steel tubing
3D printed gromits

Kegs
Regulator
02 bottle
Taps
Tower
Handful of connections

Step 1: Drilling the Fridge

By far the most important part of the project.
First I bought a Cylinda 1085 mini fridge.
It fits two corny kegs, has no freezer and was in stock at my local store.

Then to drill. I asked cylinda via mail and forum about drilling and they said "Don't" but if you must the door is the best option. That would not really work for me so I ignored them.
I followed the condensation in the fridge... it was concentrated to the back wall and nothing on the top.
So I drilled a small hole through the plastic top.
That let me poke around a little. Then I took a hole saw 35mm and spun it by hand... now I had a hole. Clean through no signs of anything on the way.

The insulation became a little crumbly. 3D printed a couple of pass throughs and siliconed them in place.

Tested the fridge still worked and started on adding wheels.

Step 2: Wheel Board

when in doubt put it on wheels.

I removed the stock feet and used a set of M8 bolts I had with an adjusting nut.
Cut a scrap piece of plywood that conveniently had been painted black to size and bolted on a set of 50mm wheels, two that were lockable.

Step 3: Countertop and Bar

I don't like the look of a fridge so I took some scrap flooring that was toungue and groove and glued a few bits to cover the top. I cut it up and drilled a few holes for the tap tower, bar mount, and for wiring (led and display).
I sanded and filled cracks and sanded again.
I then took a U profile in aluminum that was a good size from the scrap pile, sandblasted, primed and painted that, then I stained the other bits too.
The stain is an outdoor furniture stain that I have tried earlier on a table and I believe is fine on its own but since I am using softwood I also brushed on clear boat varnish that is quite hard.
On to the sides. I bought a sheet of 7mm plywood and chopped it up to fit the two sides and back of the fridge. Then I stained them. I am not ready to fix them to the side yet though.

Step 4: Glue on the Stuff.

I took a silicone from the last project I had and fastened the Counter on to the top of the fridge.
Then I again used silicone to hold the plywood to the sides.
The back plate needed a different approach, here I used steel angles that I screwed onto the wheel board and under the counter tops overhang respectively. Then ran a nut and bolt through the plywood.
Finishing everything with a 25mm trim that I also stained.

Step 5: Plumbing

I bought a duel tap tower off eBay, then a connection kit from my home brew supply store, and a soda stream bottle and regulator also from somewhere... the connections were straight forward. But the pre assembled taps shot my test water out of every connection. It was pre assembled with a 12mm hose over a 6mm connector... wish I had checked but it was solved by addding a sleeve between the two.
I did use thread tape on everything that avoids beer. The beer lines I relied on the fittings to fit and they did.
I also made a little shelf that hold my keg level and that I can tie my cylinder to.

I then trimmed and cleaned up my lines the best I could.

I tested everything by filling the kegs with water and waited for it to carbonate.