Time passed again...
There was a question on the Lead Adventures forum about roof access, and this prompted me to put a cheap and simple roof hatch together.
First, find one 25mm square blank base and one 20mm base (it can be blank or a slotted one).
This particular 20mm base has a small feed pip at the centre, which needs to be filed flat.
The 25mm base had writing and ejection marks on the underside. These were also filed flat. Check that the 20mm base fits snugly and flat inside.
Once that was completed, the underside of the 25mm base was liberally coated with liquid poly, and the 20mm base placed inside.
If you have them to hand, you can use a staple as a handle, or as I did, bend one out of 0.7mm brass rod. Drill a suitable hole (or holes) and glue it in place. I added a plate of thin Evergreen strip as a base plate for the handle.
This is a turn and lift handle.
You can then place (or glue) the roof hatch on your building.