Start small and close to normal life. A tray at the kitchen bench, a tub on a towel, water in the bath, rice or oats outside, dough while you make dinner nearby. Sensory play does not need a special set-up to count.
Containment helps. Trays, tubs, drop sheets, the bath and outdoor spaces make mess easier to live with without taking away the value of the play. Household materials often do plenty: water, pasta, flour, oats, dough, soap foam, ice and mud.
If your child dislikes messy play, do not force it. Offer a spoon instead of hands, begin with dry materials before wet ones, let them watch first, keep a cloth within reach, and let them stop. Refusal is a preference to work with, not a problem to push through.
A little adult involvement is often enough. Sit nearby, name what you notice, offer words like rough, cold, heavy or sticky, then let your child lead. You do not need to turn it into a lesson.
And remember that reducing input counts. Turning down lights, cutting out tags, lowering noise, decluttering a space or giving warning before an intense sound may be the most useful change you make.