Couple of things you can try, mostly of them, at home --
1. Make a band -- use pots and pans -- need to be able to stand the noise.
2. Large box from an appliance store -- can be made into anything -- help your child cut out doors and windows -- call the store in the morning or night before and see if they have any you may have.
3. make an alien -- need large paper/ tape together some opened up brown paper bags -- have your child lie on the large paper and trace his shape, then he can color/paint it any way he/she wants and it is his alien.
4. Play dough -- I basically save this for rainy days, so my kids look forward to it.
5. Put on the rain gear (if it isn't too cold) and go to the park to jump in puddles. It always helped me keep my kids out of the puddles on the way to church and school, because I gave them time to jump in the puddles. Then we would come home and take a bubble bath and play with bath toys. I can easily burn a couple hours in a long day.
6. McDonald's playland
7. bowling w/ bumpers but 3 might still be young for this
8. Finger painting -- I loved this as a kid, my daughter liked it, my son -- not so much. But it is worth a try.
9. Fort building with sofa cushions and sheets -- I have a four post bed, and I'll tie a rope and hang curtains, then we'll have picnic inside, then learn to use the washing machine! This usually leads to matching socks, which little kids can actually find fun -- go figure.
10. Read a book, recently, we did Harold and the Purple Crayon, and then let your child draw pictures and tell you the story, my 5 year old just did this -- this might be too old.
11, Bake cookies/ biscuits -- anything that can be rolled and cut -- they love that part, even if you have to throw some of it away, and just eat the one you actually make. They still have fun.
Well that is all the idea I can come up with right now. I have to take my 11 year old to school -- I wish she was 3 and I could spend the day doing these things with her. It goes too fast.
Have fun!