I'll need to add a lot more vertical scenery with aerial routes & line-of-sight yet, but as basic blocking terrain which captures the right feel, I think these will see plenty of use. I used PVA glue to secure the bits, strengthened with hot glue gun in places. They have a nice weight to them, & seem very durable. A black matte spray paint undercoat was essential as the plastics of the cartridges wouldn't take brush paint without it.
Lastly, here is a photo of these pieces prior to detailing & painting, where the components are clearer to see >