Advice on cheap Sensory items

Hi everyone, 

Mum to two autistic children and one in the process of being diagnosed

I'm new here and wanted some advice on any cheaper d.i.y Sensory items

I've previously made a Sensory board with door locks, light switches, uv rope (cut short for safety) and framed a piece of artificial grass.

They seemed to have grown out of these now age 11 and 13 and I'm struggling to find something to replace them with something they would be interested in. The Sensory boards really help with sleeping as they lie and play with them (they are put onto the wall by the head of their beds)

Does anyone have any ideas? It would be much appreciated