There are people that have made almost entire houses out of old, glass bottles and the effect is spectacular. We saw one of these houses and decided to do a test.
Where the first room we built meets the second set of rooms, there was a small, irregular space. So we decided to fill it with bottles.
It is not hard to do, but it is time consuming, as you can only go up so far before the mortar begins to ooge. Perhaps on a larger wall, you would be able to to one whole level and then return to the beginning to find the mortar dry enough to continue. This is not the case with a small wall.
Bottles, of whatever size and color that you want
Rebar or other roof anchors
The key to making the wall truly beautiful is a design. Put on paper how you want the bottles to go – facing in or out, what colors, are they in a spiral or straight, etc.
Make the plan simple, especially for your first try and then see if you can replicate it in reality. We would suggest that you start off with a small test wall, just for practise, before beginning a big project.
You can use either concrete or adobe for the mortar. You can buy pre-mixed mortar, or you can mix your own using sand, cement and lime. You want to mix your mortar as dry as you can, as dry concrete is not only stronger, but it will sag less.
As you get near to the top, be sure to include some form of tie-down for your roof to connect to. A good way is to put some L shaped rebars down into the wall a few layers, with their tops sticking up and the horizontal part of the L under some bottles. Make sure these anchors are in concrete and not touching the glass.
We enjoyed doing our little wall, slow-going as it was, and we hope to do more, when our time is more leisurely.