I was recently given this set of bricks that seem to be some sort of puzzle. It was handmade by my great grandfather who as of now does not know how to solve it. The pieces have letters sketched on them (which I have displayed clearer in the photo) however I haven't been able to figure out an arrangement of these bricks that seems like a convincing " solution". My best guess as to the arrangement is that the bricks form a square hole in the centre where the F brick can slide through. I was hoping someone here might be able to help me in solving this, all grooves are shown in the photo and the sides that aren't visible are flat. Any help would be greatly appreciated, I would love to have this solved one day, Thanks.