It may look like I'm getting the Christmas stamps started a week early, but these stamps from Malta from 1967 and 1968 were perfect for the 'unusually-shaped' theme.
I'm not sure how these 'stable-shaped' stamps were arranged on a sheet, I think it might work with the second row of stamps inverted.
As for size, the Soviet Union often issued large stamps, these 2 are from 1987 from a set to commemorate the 70th anniversary of the revolution.
I'm participating in Viridian's Sunday Stamps, clicking the icon below will take you there.
Thanks for visiting.