Let me start off by saying this, it may not be usefull but I did it because I could. I don't care about the dust and if you do this too, I am not responsible if you screw up.
For some long time I felt the desire to create a custom pc case coming from a Cooler Master K-380 with a few small mods here and there. Most of the time I thought about wood and acrylic but the raws were not worth my money (as a 17 y/o without a job) or I thought of a Lego case but I either had to mix colours (I hate that) or buy a lot of extra pieces (again the money). After some time the thought of building a case out of K'nex instead and after a bit of research on the internet for possible problems I decided to start designing and building the case.
My idea was to have a few main compartiments, I wanted to put the motherboard with everything in it flat on top with the PSU, the HDD, SSD, optical drive, card reader and front USB-hub (ripped out of the poor K-380) in one layer underneath it making it a low profile machine.
My specs are:
i7-3770k @4.8GHz
inno3D iChill gtx 970 airboss X3
Asrock Z77 extreme 4
CX750 (non-modular)
Deepcool gamer storm Lucifer
Samsung 840 evo 120GB
WD caviar black 1TB
Creative sound blaster Z
2x4GB ICIDU 1600MHz ddr3 value ram (OC to 1866MHz)
1x8GB Crucial 1600MHz ddr3 value ram (OC to 1866MHz)
Also some random optical drive, some LED strips, a card reader ripped out of a 13 y/o pc, the front USB-hub from my old K-380, the fan out of a Coolink corator DS LGA2011 I had lying around and 2 scythe slip stream 120mm 1900rpm fans
Once I had figured out how I wanted it to be I grabbed my boxes filled with K'nex and started piecing everything together slowly.
I started with the construction of the lower compartments, I built the cage for the HDD with the right above it and with the PSU next to it for the rear of the case and after that I made the front with the cable storage for the non-modular PSU and the cage for the optical drive including mounting places for the card reader and front USB-hub. After I finished them I linked them together with a little bit of space inbetween for cable routing completing the bottom part of the case rather 'quickly' (took me only several hours to build).
At this point you might ask: "How d*f*q is a motherboard gonna sit on that?" The answer is: "Not." If I were to just mount the motherboard on some knex it would cause static electricity when I were to put it on the floor burning everything (in case it isn't clear, I don't want everything to burn, yet...). I got a really old PC case (the same one I got the card reader out of) and took the motherboard backplate out of it. I was gonna tie the backplate on the top of the K'nex case with some isolated iron wire and mount the motherboard on the plate once I had the whole thing put together. After I mounted this and connected everything I stood on it and started picking up stuff while standing on it, it can hold at least 90kg of weight on the top without components inside. Also while drilling some of the connections out of case I got the plate out off I broke a drill bit.
Quite soon after I finished this I realised I completely forgot to mount the on/off and reset button together with the HDD and power LED's, so I grabbed it, went outside and started drilling and glueing, it may be scrached but come on, it's homemade, it can't be perfect. I got the LED's out of an old, broken mouse (one blue and one red) and the buttons out of another old case (at this point I have 3 metal cases in my room and one K'nex made one and none had any components in).
It was time to start putting everything on the case so once I took everything out of the K-380 I started building starting with the lower compartment and everything besides the motherboard. After putting everything in it I hooked up the cables I already could and did some quick cable management. I also used isolation foam tubes to reduce the HDD noise as you migth or might not see.
Once this was put together all that was left to do was to just drop the motherboard plate on top of it, mount the thing, connect the last wires and done, weeeeeeell, NO. Connecting all the K'nex connectors in the middle was a straight up B*TCH with spaces being as tight as 2cm while being right in the middle of the case with all the components around it leaving no room for my hand to reach and connect them. Eventhough it was K'nex my hand hurt like hell afterwards because it got jammed multiple times and all I could do was yank it out. However, once I did manage to connect every single one of those little sh*ts I mounted the motherboard on it, hooked up all the cables, added a 3rd fan to the CPU with the same wire used before and it was done. Sadly during the installation of the motherboard one of the reset button pins bent but I managed to get it straightened out enough for the reset button to fit over it.
After I took these pictures I still replaced the yellow sticks with gray ones and replaced the bottom white circle parts with black ones.
The K'nex parts used:
32 smallest black sticks
297 small white sticks
121 slightly small blue sticks
16 medium sized gray sticks
15 1-slot gray connectors
2 2-slot, straight brown connectors
22 3-slot gray connectors
3 5-slot gray connectors
8 white full circle connectors
22 black full circle connectors
120 half circle combinable gray connectors
86 full circle combinable blue connectors
2 small gray plates
17 small black plates
16 large gray rings
12 small blue rings
Total: 791 K'nex pieces
As far as the effectivity goes, the noise dampning is different, as there isn't any it is louder but because there is no case that can shake around making noise it's also quieter, I would describe the sound as different, not louder, not quieter. As for the thermal performance, all the components that kick out heat are exposed to open air giving them all the air they need to cool actually resulting in 8oC lower temperatures. The dust is one bad part about it, simply said, it collects more of it, luckilly my room isn't dusty at all (didn't have to clean the old case once in the 2 years I had it) so I guess I may only need to clean it once a year.
Summary of the build, it was one hell of a lot of fun to do although there were some less fun parts. *mumbles quietly: "f*cking b*tches, those sh*tf*cks in the middle"*
Building your own case out of K'nex is a great thing to do when you have some creativity, like building, want something of your own and a lot of parts leftover from when you were little (or like me, still play with them from time to time).
If you have any questions, be sure to ask them and I will try to answer as quickly as possible.
EDIT: I forgot to add my RAM, I added it.