The newest design has a spacer . It is why I have been getting away with the 3000 rpm fans.
I use 4 things
Some 2 by 4 wood
some silicone epoxy
some metal tape
some screws
I cut 3 pieces of 2 by 4 into trapezoids
I silicone them into 1 piece
I wrap them with metal tape
I put them into an s9 shell.
You can use wood glue or silicone epoxy
here is a you tube of assemble with silicone epoxy. it is in 3 parts.
1st video
https://www.youtube.com/watch?v=KYw5PxWqRSg2 more videos coming.
more on assembly of air flow guide
https://youtu.be/Ttt5HsUUDI8third video will come in a while as YouTube is slow to upload today.
I am really pleased with these air flow mods.
https://www.youtube.com/watch?v=QNri1LpEGAU&feature=youtu.beAt this point I am going to run 2 1 board units over night.
They are fully built and I will be test and comparing them for 3-4 nights.
In 5 nights I will be running a third unit with 1 board and really good fans hi end long life fans from san ace.
made of metal not plastic. they are 4700 rpm fans and fairly quiet.
So I should have 3 comparison units. fully tested by next weekend.