Identical Coloured Nets

Net Problem from UKMT Senior Math Challenge (2014)
Solution here.

Regular Star Polygon made of Trapezia

Angle/Polygon Problem from UKMT Senior Math Challenge (2014).
Solution here and extended solution together with note on original inspiration for problem here.

Tetrahedral Die Problem

Patterning Problem from the UKMT Junior Mathematics Challenge (2014).
Solution here, extended solution and suggested investigation here.

Quadrilateral Areas Problem

Area Problem from the UKMT Intermediate Mathematical Challenge (2015).
Solution here and extended solution here.