Last night I came up with the idea for this marble diamond. I think of concrete as being sort of a classic material but it is certainly making the trend right now. It's also pretty easy to work with. Since I made this in the evening I don't have photos of the process but it was a simple process.
I used this template, printed on printer paper.
Then I lined it with some clear packing tape, otherwise the wet concrete will soften the paper and it won't hold a shape.
Once I covered it in clear tape I cut out the template, folding twice on all the lines to give them a good crease.
Also, don't worry about folding the top part down, that will be your opening to pour into.
I then stuck the pointed part of the paper diamond into a paper cup and poured my concrete mixture through the top.
I used a quick dry cement so it only took about 2 hrs before I could peel the paper off.
I let it dry over night but it's still a little damp, even though the sides are solidified now. (It will lighten in color as the rest of the moisture is evaporated)
Once it's completely dry you can spray paint it a metallic copper or matte white but I think I prefer this imperfect finish, bubble holes and all.