Cover a low table or board with clingfilm, squirt paint over it, cover it with more clingfilm. You can push the paint around and there is no mess!
Cut roll loos in half and tape them to a wall so a ball can be rolled down/between them
Cover the ends of loo rolls with paper and fill with different herbs and spices - child can shake them for sound and smell for sensory. If they get bored, poke holes in the paper so when they shake them the herbs come out (suggest you do this outside or over a tray!)
Wet herbal tea bags (lots of flavours) and use them to make marks on paper
Homemade play dough
Fill a tray with shaving foam and hide toys in it
Collect branches from the garden and use them as paintbrushes
Thread pasta on to string
Freeze toys into ice so they can break them open
Explore recipes - put all the ingredients for a cake in a tray in little bowls. Explore them, mix them, talk about them, etc. If you’re feeling adventurous you can actually make them but baby will be happy just exploring the ingredients and mixing them up!
Posting games - cut holes in cardboard boxes and give different items to post (pasta, balls, etc) make sure not all holes are big enough to teach about size etc
Colour matching games - put colours circles on the floor and encourage baby to put correct colours bricks etc on them
Give a doll or toy animal a bath, make them dinner, feed them etc
Set up plastic bottles and bowl with a toy ball
Make a toy water slide - cut tops and bottoms off of plastic bottles, tape them together and pour water in at the top. Put toys down the ‘slide’ if you don’t want it to be messy, do without water
Organise toys into size order, then colours, etc
Tape lots of paper to the floor so they can draw on it. If you want messy, get the to step in paint and walk over it
Do some gardening - plant seeds into pots. You could paint the pots as well!
Get a bubble machine - I know you didn’t want to buy mich but I swear they are worth the money! They are good on their own or they can add a sensory element to other activities
Paint the garden fence - give them a brush and a bucket of water. The water will darken the fence but not actually paint/damage it. You could also let them do chalk drawings on the fence and then blast them clean with the hose!