Finally got round to trying this - my first time for FPP, I've never really worked out how it's done so thankyou Syrinx it's now crystal clear. I enjoyed doing it especially when I got into a rhythm but if I was doing any more I would have to move my cutting mat to beside my machine. As it is I had to keep getting up to go round the other side of the cabinet every time I trimmed. I did find it difficult to place the triangles to end up with enough seam allowance on the edge of the block. I know I've cut off my seam allowances along the top - I got carried away on the second one and tore off the paper before I had trimmed the block and then forgot to leave the 1/4" beyond the points.
Anyway, here it is.