For a mining case, I use BBT style cases built out of two 8ft pieces of 1/8" x 3/4" angled aluminum, one 4ft pieces of 1/8" x 3/4" angled aluminum, one 8 ft 1" x 3" piece of pine, one 4' 1" x 2" pine and #8 1/2" self-tapping screws I get at Lowe's. The case will easily fit 7-8 RX 4XX/5XX if you put them about 1.5" inch apart. The cost of the aluminum angles and screws was ~$45. If you build it out of all wood, the cost would be less than $10.
https://www.youtube.com/watch?v=D5xNrlxsCVshttps://www.youtube.com/watch?v=MA_sH4q2toU&feature=youtu.be&t=2837-8 card frame (Dimension 24" W x 15 3/4"" D x 10 3/4" H):
Build Cuts:
For the Angled Aluminum:
First 8ft (96") Angled Aluminum; 5.75 inch of waste
4x 15 3/4" cuts (58" use) - (Case Depth)
3x 10 3/4" cuts (32.25" use) - (Case Height)
Second 8ft (96") Angled Aluminum; no waste
4x 24" cuts (96" use) - (Case Width)
4ft (48") Angled Aluminum; 37.25" left over
1x 10 3/4" - (Case Height)
And for the wood:
1x3 Pine (Case Bottom):
6 cuts of 14 1/2 (87" use)
1x2 Pine (Card Bracket Support):
1 cut of 24" (24" use)
I also built a 14-15 GPU double tier case for a new build I'm doing with the ASRock H110 BTC Pro mining motherboard. Lots of room underneath for multiple PSU's and the double tier lets me use a single box fan for the whole rig.
14 GPU Double Tier Frame - (Dimensions 29.5" W x 16" D x 17" H):
Build Cuts:
For the Angled Aluminum:
-First 8ft (96") Angled Aluminum; 95.5" use 0.5" waste
2 x 17" cuts (34" use) (Case Height)
2 x 16" cuts (32" use) (Case Depth)
1 x 29.5" cut (29.5" use) (Case Width)
-Second 8ft (96") Angled Aluminum; 95.5" use 0.5" waste
2 x 17" cuts (34" use) (Case Height)
2 x 16" cuts (32" use) (Case Depth)
1 x 29.5" cut (29.5" use) (Case Width)
-Third 8ft (96") Angled Aluminum; 88.5" use 7.5" waste
3 x 29.5" cut (88.5" use) (Case Width)
And for the wood:
-1" x 3" 8ft (96") Pine; 96" use no waste
6 cuts of 16" (96" use) (Case Bottom)
- Left Over 1" x 3" 4ft (48") Pine; " left over
1 x cut of 16" (16" use) (Case Bottom)
- 1" x 1" 8ft (96") Oak; 59" use 37" left over
2 x cut of 29.5" (59" use) (Card Bracket Support)