Average Joe

Stay with i5 and change the PSU later on when you will afford it.

I'd run into no post problem. I was sure that painting the mobo was not the issue. It turned out that  I had to flash the bios to run i5 4690k . I had one iteration older bios than minimum to run it. Thankfully I have a second rig with i3 4330. So this build is up and running. Still some cable management and overall cleaning to do.

Still in progress:
 
https://twitter.com/AvgJoe412/status/734422675553189889

What MOBO and CPU?
 

PSU sleeving complete. Took me in total 6h but it was worth the time.
 
And yes. I've changed the fan too.

My answer is - "In the future"

As for the case - it's for cordless 12V Makita 6271Driver-Drill
My rotary tool is an 8 year old PROXXON MICROMOT 50 (little green-yellow case on the left)- it never failed me.
For cutting the window I used Makita 4326 jig saw and the Proxxon for the "corners".
As for the files, don't worry i have used them many times before + the cuts are pretty straight not much material to get off.
 
For the plexi - same technique as with glass. I cut (more like a scratch) it a bit with precision knife and then bend it on the cut. Fast and clean if done right.

I wasn't able to make any progress last week. But here is DIY Backplate with 3 layers of primer and 1 of coating, still 3-4 layers to go.
 

And here is the card with backplate. Sorry for the poor lighting, will post better ones later. I decided to leave the card plastic shroud black.
First of all it goes with the theme and secondly there is very little of it visible.
 

Window cutout done. Now I need a lot of time with a file to make it beautiful.
 
 

Nope, allegro. But after the fact I saw that the shop that I ordered it from is located just 20km from where I live. You can also check local auto parts shops for it.
And after that I noticed that the label states that distributor for Poland is located in my town.
 

EN: Thanks. The motherboard was painted with plasti dip like rubber paint called THIS. There will be more photos soon.
PL: Dzięki. Płyta jest malowana gumą w sprayu coś takiego jak plasti dip o nazwie THIS. Wkrótce więcej fotek.

Of course you can. But that does not mean that you should.

As requested some more Pictures of the motherboard. As you can see I did not paint most the power section (from the one painted on accident I removed the plastic). I will add some radiators there. There is some excess paint here and there, but it's easy to peel the excess off.

 
 
 

Always go for single card vs. SLI/CrossFire. The support for SLI/CF in games is let's say questionable.

I have the same situation here, but I would rather go gtx 980 or 980ti. I'm not a nvidia fanboy I had ati/ radeon cards as well as nvidia.
But then again I'm a patient person