Octiamond Constructions

The hexagonal ring at the bottom left was made by hand in the early 1970s and the one at the bottom right was produced by computer in July 2000 by Patrick Hamlyn. Notice that this is made of six trapezia which could be combined into a number of other figures.
Patrick has also found some constructions with series of holes in a shape similar to that of the main figure.
There are 120 one-sided octominoes covering a total area of 960 unit squares. This set has an odd number (37) pieces with a colouring excess of 2 triangles and so no parallelograms can be made. Three trapezia should, however, be possible namely the 77-6, 43-10 and 1-30. These are shown here as well as a side-31 triangle with a single hole which is a similar hole construction.
David Bird made this construction with these pieces by hand in 1973.

Patrick Hamlyn has found fifteen hexagons using the one sided octiamonds. These are shown below with a set of three congruent pieces also formed with the set.