I'm using black felt at the bottom, a small tin can, and black sponge around the inside of the can. I hot glued them onto the can, and then put 91% isopropyl alcohol in it. Afterwards, I used some clear wrap and put it over the top, then put a rubber band over it to make sure nothing came out. Instead of dry ice, I used a can of compressed air, and the bottom of the can has ice molecules on it, but I can't see any vapors. Any tips? Thanks
All cloud chamber designs based on IPA that I've seen - require cooling down to -25°C and lower. It is unlikely that you consistently reach this temperature.
Also, for cloud chamber operation it is important to maintain stable temperature. Very rapid temperature gradients occurring when you cool it with compressed air cans - also do not allow to achieve stable supersaturation of IPA vapor (actually it's not compressed air in most of these cans - it's typically some gas which is easy to liquify).
I suggest to go with dry ice. I've just asked similar question regarding rising optimum temperature of cloud chamber: Near-room temperature DIY cloud chamber?