Bit of a flurry of uploads having been on holiday for a week - armed with foam board and cutting gear mind you!! I cut a stack of  oblongs measuring 2cm x 2.6cm (width of the metal ruler), then marked them up with a mix of the following combos, all top left corner marks are 5mm in, bottom right marks are 5mm, 1cm and 1cm left to right. Middle lines are then 1.5cm from the top on the first 2 followed by 1cm from the top on the last. The scalpel is then inserted flush with the card at the corner point across to the surface of the middle line and cut across the foam, leaving a sloped edge to give twist to the stairs.

Once I had that lot cut up it was a case of wait to get home before gluing in varying combos of the 3 types to give different twists to the stairs, adding in the occasional flat area too.

A bit Escher like with changes in planes of gravity etc, this will be added to by humanoid figures on upper and lower surfaces of the steps - pic of one side installed

The mausoleum base is 2 sheets of foam board glued together with added BBQ skewers underneath - this goes right through the backboard supporting the resin model kit in mid-air. Once the stairs are completed the underside of the Mausoleum will have chunks of foam added to build up a rocky look as if it's been ripped from the ground - at least that's the plan!

First of the right side stairs added, one more to build! all the foam board is stuck using superglue, this one pictured is from a £1 shop, seems fine for this sort of scenery build but highly advise windows open for this quantity of gluing!!