We are finally fixing up the playroom in our house and I am excited to actually decorate a room (as opposed to removing wallpaper and sanding and painting!). I love this picture and want to do similar- neutral walls with lots of cheery colors. And I want to have a banner like this across the room or a wall.

How would you do the banner? I'm thinking of buying a bunch of felt squares in rainbow colors and hot glueing over long string of twine. How big do you think the triangles should be to pop? It's a big room but the ceilings aren't that high. I'm fairly crafty but don't see much or have a machine. Or have you seen anything similar for an affordable price?