Of the 8 figures with all three pairs of elements merged 2 are the same as order 3 demisymmetric tiles and 2 the same as order 5 demisymmetric tiles. The remaining 4 are shown below.
Two copies can (obviously) be put together to tile a symmetric tile. The images below show one copy in red, and a copy rotated 180° in blue.
© 2015 Stewart R. Hinsley