I did the exact same as you, basically took a pen tube and cut it in small pieces and used those as the "spacing" between the wood and motherboard.
Love the pen tube idea! What I did on my side is I used self adhesive bumpers and drilled mobo through them.
When i first started my 1st rig, got a nice rack blah blah.... when I decided to go full steam ahead in 2016, speed to deploy was the essence and built the miners around the full height rack itself, with GPUs hanging via metal S hooks.... then when space and GPU density came into play.... I got rid of risers all together and standardized on riserless motherboards like the K35 mostly and a few Oanda, Colorful motherboard variants. You can find the pictures of my open air rigs in one of Phil's thread. One more thing.... the biggest game changer for me was using SMOS and ditching Windows all together... that saved me tons of hours in rig building and babysitting sick rigs on Windoze
Thanks @citronick that is gold. I didn't even know such boards existed!
Being riserless is sure less expensive as well. I like how you just have to slide GPUs in there and not have to worry about fixing them. Had a look at your rigs and they look pretty slick. K35 seems hard to find, but I've seen a few Oanda mobo/cpu/RAM combos on eBay that aren't expensive, so I'll make sure to look for them for my next rig.
As of SMOS, they don't seem to support GPUs less than 6Gb anymore, so that won't work for my low-end 3Gb rigs. However, I did the math and came to the conclusion I'd better save for 5600/5700/XT instead of spending on anything else moving forward (hopefully I can control my addiction for a while). I'll sure consider SMOS at that point. 2 bucks monthly per rig is a steal... As a miner, if you consider you're paid for your time at an hourly rate just like any job, dealing with Windows issues and endless updates/reboot factor for much more than $24 a year!
Your post would definitely deserve some merit. Sadly, I still can't share the love... But I guess I will at some point!
Here are some points to give away. I will post my rig in a few.
4 cards 150 mhs 489 watts at the meter
msi 5600
msi 5600
msi 5700
visiontek 5500
smos 153mhs and 466 watts software
actual meter 489 watts.
The gear is pretty efficient better then my 1080tis
500 watts is 12 kwatts a day
so
$2.40 a day in power if you are 20 cent power
$1.80 a day in power if you are 15 cent power
$1.20 a day in power if you are 10 cent power
$0.96 a day in power if you are 8 cent power
$0.72 a day in power if you are 6 cent power
$0.48 a day in power if you are 4 cent power
this rig is earning 4-6 a day. so it is not great at my house in the summer,
but at the farm I get 2-4 a day. which is 250-500 day payback. and all the gear has three year warranty.
I would argue getting one rig four cards is fine if you don't have a lot of gear.
I had my old gear and added two thousand in new gear. it should pay off in three months since i have enough old gear.