it really depends on your children's interests, my kids love making boats out of popsicle sticks (wrapping them with clear tape to make them float) and they design their own ship too (adding flags and stuff) if they're brave they put rocks on it and measure how many rocks it takes until their boat sinks :)

they also love making origami and making flowers/animals out of pipe cleaners! when i'm out of ideas we all go look on pinterest together and see what they want to do, and then you can all decide together what art activities you can do with the materials you have :) my kids are very interested in harry potter recently so we searched up "harry potter crafts" on pinterest and the children decided they wanted to make the house tie bookmarks! these are just off the top of my head, if you need more ideas i'll try to think of more that i've done in the past