OK, found the glass-cutter, it was in the next cupboard -not in the bush.
Image below is the completed unit, it looks the same as before, but, with the "two-way mirror fitted using 2 sided tape.
Straight through eyepiece holder not supplied with unit.
Got set up for an eyeball test (Jupiter) on the 6" with 25mm eyepieces in each outlet. Images almost aligned. Straight through gave a clear image with little percieved colour change and looked bright. The right angle was notably darker with a double image, one "pink", the other "blue". Reflections from both sides? of the glass, did you get this effect Ken? Both were bright enough to guide on and the moons could be visually seen.
Looks like a go-er.
More playing to align both images.
