triangles = [[0, 30, 31], [2, 32, 38], [3, 24, 46], [4, 14, 27], [10, 18, 48], [12, 21, 35], [15, 39, 45], [17, 32, 38], [19, 32, 38], [21, 43, 44], [29, 43, 44]]
y = list()
for i in triangles:
y.append((i[0], i[1]))
y.append((i[1], i[2]))
y.append((i[0], i[2]))
print(y)
выход: [(0, 30), (30, 31), (0, 31), (2, 32), (32, 38), (2, 38), (3, 24), (24, 46), (3, 46), (4, 14), (14, 27), (4, 27), (10, 18), (18, 48), (10, 48), (12, 21), (21, 35), (12, 35), (15, 39), (39, 45), (15, 45), (17, 32), (32, 38), (17, 38), (19, 32), (32, 38), (19, 38), (21, 43), (43, 44), (21, 44), (29, 43), (43, 44), (29, 44)]