DIY Photo table for Flat Lay

Hello,

I've been working on a design for photo table. My reference/copy is: http://styleshoots.com/photography-machines

I work in a printing house where we print all kind of stuff. And lot of times I need my product to be 1:1 for me to precisely set dimensions for transfers.

So as I write this, I've did some primitive thing, mount my Camera on ceiling and placed a light under a mat glass desk. So I take 1 photo with light on so I get 100% white around my product and then one picture with light off. Combine two images in Photoshop and get alpha channel for transparency. I've automated it for photoshop to do this all on it's own with help of macro actions.

My setup atm: https://imgur.com/gpqnrYv

Then I saw this Styleshoots table ( http://styleshoots.com/photography-machines ), BUT... Costs 80k, which is waaaay out of my reach. Found some cheaper ones like ClothingPad, but still 15k is alot since I don't make direct money out of this. So I decided I'll build one myself since my primitive setup is too small.

But before I go into this I'd like some feedback and some info.

1) What lens to get with Nikon D810? I want to get all those details in fabric of a t-shirt. At the moment I use D7000 with 18-200 lens that came with it. I got white balnce set to custom and colorchecker passport with correct exposure. I take photos in ISO100/F18/1sec. Image is kinda sharp all across but I lack Details, image looks flat (usualy red and black products). For light I use D50 95% CRI lights. And my photos usualy come out flat. Myb because my lights are set 90degree on my "subject" or is my lense crap? Or is sensor in my camera too weak and can't pick up those details?

So is 2nd hand D810 + some lens a good option? They go for around 1,8k€ atm.

I'd also use this camera for "scaning" biger prints.

2) What kind of backlight is used here https://www.youtube.com/watch?v=ACi0rhurb4E at 1:47 on.

The table turns from white-greenish tint to pure black and then to white. What kind of backlight is this, Big LCD screen? I've checked those "magic glass" that turns from blackish to semi transparent when pluged to electricity but that does not seem to be the case here. Any idea what kind of sorcery is this?

Thanks

Sry for my bad english.