Definitely good ideas on the stickies in the activity board that creations mentioned.
I just gave DS2 play dough to play with for the first time the other day which he played with for a good 5 minutes, which at this point is about all I can get out of DS2 for a focused activity. As well I brought out crayons and we "coloured" (he mainly just investigated the crayons) today for about the same 5 minute time span. There are alternatives to shaving cream for the fingerprinting (yogurt, pudding) but with your DS being MSPI they probably are just as good for his body as the shaving cream
I know that I have been trying to think of some alternatives to use as I am not wasting some expensive coconut yogurt for a sensory experience, lol.
As for more sensory type activities DS2 enjoys a couple of ice cubes tossed in a glass baking dish (it is heavier so they are less temped to pick it up), also he sometimes will play with DS2's coloured rice bin. You can also put a large plastic compntainer with water on the floor on top of some towels and let him splash. But as I mentioned before you need to be realistic with your kid and their attention span. I know that DS1's seemed to be longer at this stage, but I find with DS2 if it is a very specific activity (e.g. The play dough) I can usually only get 5 minutes before his attention seems to wander...
(I know this is more for the activities board, but I was here, so I posted, lol).