What is the glass made of?
The glass is made of plastic.
    src        edge_attr  dst
0     0               on    1
1     0   to the left of   10
2     1   to the left of    7
3     1               on    9
4     1   to the left of    8
5     1   to the left of   11
6     1   to the left of    5
7     2   to the left of   10
8     3  to the right of   10
9     4  to the right of   10
10    5  to the right of    1
11    6               in   11
12    7  to the right of    1
13    7  to the right of   10
14    8          between    7
15    8  to the right of    1
16   10   to the left of    7
17   10   to the left of    4
18   10   to the left of    3
19   10  to the right of    2
20   10  to the right of    0
21   11  to the right of    1