Do you use the Sodastream? Me too. Do you lose the black caps that come with the Sodastream bottles? Me too. After spending a long time searching for a cap I decided there needs to be a system in place for keeping track of the cap. After some trial and error, I came up with this 3D printed option so that my Sodastream cap would remain attached to the bottle at all times. This is still a work in progress, but it has already been a big hit in my home. I hope you enjoy it as well.There are 4 printed parts needed - the piece that covers your sodastream cap (Cap Cover), the Cap String Connector, the Cap Top, and the Bottle Sting Connector. Only 1 piece of each part is needed. You will also need a ¾ velcro, and some string. Underneath the cap cover is a ¾" x ¾" square for a piece of velcro to be placed. The opposite side of the velcro is placed on the center of the cap. Place the Cap String Connector over the Cap Cover, and then place the Cap Top onto the Cap Cover. It should lock in place due to friction. This should allow the cap to spin freely. On the underside of the Bottle String Connector is a similar square. Attach another piece of velcro to the underside of that piece and attach its opposite to the side of the bottle close to the Fill Line indicated on the bottle. Attach a piece of string from the Bottle String Connector hole to the Cap String Connector hole. That's it. Never look for that little guy ever again!