Reddit reviews uxcell a15011600ux0309 D-SUB DB15 VGA Male 3Row 15Pin to Terminal Breakout Board Connectors

No OP but I've built and help people build these before. Here is my boilerplate getting started guide

So these are the two main pieces you need to build a control box to connect to your computer. Additionally I'd recommend some sort of enclosure too, but its not needed and can always be added later.

Additionally both of these parts can be found cheaper on ebay vs amazon, but usually take a bit longer to receive via ebay.

https://www.amazon.com/D-SUB-15Pin-Terminal-Board-Connectors/dp/B016FBVIJY?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

https://www.amazon.com/Easyget-Arcade-Encoder-Joystick-Fighting/dp/B00XHRIKLE?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

The ZD encoder looks like a joypad or game controller to the PC. All you need to do is cut off the metal ends of the wire you use, and use the screw down terminals on the VGA Terminal breakout board.

The pinout is shown here and should work
http://pinouts.ru/Game/cobalt_flux_pinout.shtml

The main thing is that you connect the grounds to grounds, and the directions to a button. Overall it should be VERY easy once you have everything in front of you, because it doesnt matter what button you wire up to each direction since you set things in Stepmania by stepping on the direction, and it wont care if it corresponds to button 1 or button 16.

I am here for you in your time of need!

Here's what I used:

A USB Encoder: https://www.amazon.com/Reyann-Arcade-Encoder-Joystick-Fighting/dp/B00UUROWWK/ref=sr_1_3?ie=UTF8&qid=1522934637&sr=8-3&keywords=usb+encoder ($11)

A VGA cup (double check that yours is 15 pin, some of the very early cobalts were 9 pin, I think): https://www.amazon.com/gp/product/B016FBVIJY/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1 ($10)

With the D-Sub, if money and time isn't a problem, shell out for one that comes with an enclosure like this one: https://www.amazon.com/MyCableMart-15pin-Connector-Repair-Solderless/dp/B01N45B2PV/ref=pd_sim_23_4?_encoding=UTF8&pd_rd_i=B01N45B2PV&pd_rd_r=BDEX1B1V5S71ZSB7YCXH&pd_rd_w=LBp2Y&pd_rd_wg=zzOED&psc=1&refRID=BDEX1B1V5S71ZSB7YCXH

It's a lot tidier and protects your wires a bit. If money is an option and/or you're good at soldering you can get a solder one cheaper. I like these because you just slip the wire in and tighten the screw. The screw is weaker than a solder but that's not going to be the weak point of connection and try not to trip over your wires anyway, please.

You also need a small screw driver and either a pair of wire strippers or a pair of scissors and some precision. The process of wiring it is going to be pretty easy - the USB encoder comes all the wires you're going to need - we'll use the red and black ones. You'll cut off the ends, strip them, and connect them. I can walk you through this process when you get your parts but really you just need a picture of the end product... which I'll get you when I get home.

Previous folks have mapped the pins for us: https://imgur.com/TX7jvnZ

The only important one is that ground. There's going to be a "GND" marked on your DSUB, but don't connect it to that, you need to map the Ground properly. The rest of the pins can be connected to whatever, because you'll be mapping the buttons in Stepmania. Get the parts, I'll take a picture of mine at home and when you have the parts in, I'll have some images of my strip and connection process up in a gallery. Otherwise I'll sell you mine for.. like... $35, plus shipping. It's not worth the price since I haven't bothered to print a box for the encoder yet, so just make your own :D

I actually made this thread a few weeks ago over on the Stepmania sub. See the comments here

Your best bet for a control box is to build your own, unfortunately. I built one, and would be glad to help you out if you have questions, but it's actually surprisingly straight forward (I only know how to make a USB one for PC though). All you need is a USB Encoder and a 15-pin VGA.
I soldered mine, but with this VGA you can just strip the wires and screw them in the terminals. You'll need the pinout diagram to reference and figure out which pins to use. You'll only need to connect wires 1-10 because there's no Start or Select buttons. I can take a picture of my finished product if you're interested to give you an idea of what you're looking at

I think you are going to have to make your own. Here's some links from a comment I made from a year or two ago:

Hey! Here is a guide that will tell you everything you need to do and it doesn't require any electronics knowledge at all: http://www.stepmania.com/forums/input-adapters-and-controllers/show/5493

I made two of these and they work great. With the pinout, you're pretty much set.

The only thing that I needed to purchase that the guide was not 100% on were ferrite cores - I recommend you getting these. They are little cylindrical clasps you put on to wires that help with interference. All parts linked below:

https://www.amazon.com/gp/product/B016FBVIJY/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B00UUROWWK/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/Gino-Suppressor-Ferrite-Filters-a12071000ux1058/dp/B009ENG6TI/ref=sr_1_6?ie=UTF8&qid=1474499132&sr=8-6&keywords=ferrite+core

edit: here is the pinout for the cobalt flux http://pinouts.ru/Game/cobalt_flux_pinout.shtml