Those look good, but I see some issues with them that are a real deal breaker for these in quantity (which may be fine if you aren't looking to do higher quantities):

1. It's about 1" too high and looks like it could be lowered 1" without causing clearance problems.  The 1" would facilitate it being able to be put into a 1/4 cab rack in pairs.  With the current height, you can only get 1 in a 1/4 cab with 90% of the space needed for a 2nd one going to waste.
2. They don't look like they can be stacked and have no provisions for mounting in a rack from the pictures.  Ideally, being able to stack them in a rack would be awesome.
3. Is there space for 2 PSUs?
4. With #2 the hard drive placement makes stacking difficult.
5. Nice to have the option to move the cards closer together to have 5 (or 6?) cards in one machine.  I would like to run 5 cards per mobo, but 4 is nothing to sneeze at. You don't need a lot of space between cards to cool them, which brings me to the final #6
6. There doesn't appear to be any place to mount fan(s).  Regardless of it's open air design, if you put these in a rack, you absolutely need to get some airflow going from front to back.  Being able to mount a couple 120mm fans on the front blowing across the cards towards the back would be important.

Otherwise, these look pretty cool and I'll probably get at least one for my own personal use if not a couple.  If nothing else, they'll make interesting desktop cases

Absolutely none for a rack case/mining rig.  As a desktop case, I'd say somewhat important. 

I think that you could mount both an HD/set of HDs and an optical drive on the side and "inside" the case, so even if you wanted to rack it or stack it and still maintain your drives, that would be ideal.  Now that I think about it, actually would be pretty awesome to be able to stack theses even on a desk where the bottom of one will fit into the top of the other one to provide some stability. 

Just for reference, 1/4 cab is usually 10U, giving you 17.5" of vertical space.  Most cabs are 19" wide, though I hear there are 23" ones, but I've not ever used those variants. 

If you were so inclined and needed more room, you could stretch it out a bit, since there's plenty of room in a cabinet from front to back.

I need a mining chasis that supports 7 cards.  Maybe you can take the idea and have a 7 card "special order" option. 

Received cables i ordered on 16th in 7 days to my home, India with customs clearance.
I was in fear that 27% customs has to be paid, but courier guy just gave parcel & went.

But, small mistake.
I ordered 21 nos. 1x to 16x modified extender & 2 nos. 16x to 16x extender, & i received the same only. I counted it to verify.
But, the customs dispatch deceleration note says, 15 + 2 =17 only with a value of 240+ USD.

Is this made me customs clearance easy?

I give +1 or +23 to cablesaurus for door delivered to me in one week in perfect condition.
Thanks.

I wish I had seen this last week   I bought a few extenders from some chinese seller on ebay and its taking forever to get them

Do you have any pics of the mining chasis yet?

My partners and I have taken several suggestions into account and are working on several changes to the Chassis to be released imminently. We will have pictures and tons of details available soon.

Another vouch for great service, got my cables fast + great communication!

Daisy chaining DOES NOT WORK.  If you get it to work at all, your system will be horribly unstable.  This is unfortunate, because as far as I can tell, it's impossible to get longer cables than the ones Cablesaurus sells for a reasonable price.

That said, I've bought several cables from Cablesaurus, and they work just fine, and service has been great.  There was a small miscommunication in which I was sent a x1->x16 w/ molex cable instead of a full x16 w/ molex cable.  He sent out the proper cable immediately at no charge, and I used to x1->x16 in the meantime.

By the way Cablesaurus, I picked up some envelopes today, so I'll send the x1->x16 cable back to you as soon as I get a chance to go to the post office.

Bought a couple of them a while ago great service and communication.