Progress update! Because I want the centre half pipe to be removable so I can get to the gubbins inside, I've decided to use the centre beam and piano key greeblie as the retaining clip. I'll add a magnet or two for extra security. And yes yes. I know some of the angles and measurements are off a little, alas the joys of not many actual full measurements of depths etc. So I've had to guess and eyeball a lot of it. But it's getting there! And yes yes. I know some of the angles and measurements are off a little, alas the joys of not many actual full measurements of depths etc. So I've had to guess and eyeball a lot of it. But it's getting there!