those kids are pretty young. I have my tiny dining room dedicated to free art for older kids only. 3 and up typically, depending on their experience level. My own two year old is allowed too. I love having this space for messy work and sensory tubs and stuff. I just gate the little guys out.
I will bring art supplies to the toddlers and supervise closely because mine are too wild with it yet too. i give them little bits of time in the workshop as they get older/more mature and when they start acting a fool, I remind them of the rules once or twice then put them back into the playroom.
Even as they get older, you have to have a place that it's ok to play, kwim? Do you have a porch area...you could lay Ia tarp on the floor, is your kitchen large enough for a little art table? Even with experienced kiddos, there will be mess and fretting over the spills will ruin the experience for everyone.
The reggio studios seem like they would never be workable in my world. Maybe Italian children are more disciplined, lol...or maybe the teachers have more time/patience for mass scale organizing.
I have one tub for drawing stuff (crayons, markers, pastels, chalk), one for glue, scissors /collage materials, one for paint, brushes and palettes, one for playdough and playdough toys...and few other various random things, small wooden blocks etc.
Children, particularly older preschoolers need these materials to express themselves. if you can find a place for that to happen (a kitchen table with a big basket full of stuff?) You'll be really glad you did.
sorry this got so long.
