First of all, you can use a thermocol or cardboard as your base.Then for the lung part you can cut out a lung from a sponge and then stick it on your base. For the ribs, you can use copper wire. Then for trachea, you can use a pvc pipe...or simply take a few straws and tie them together with a rubber band.Use the same tube like structure for the bronchus.You may draw the rings of cartilageUse small pieces of straws or copper wire for for bronchioles. For the alveoili, you may either use some drawing pins or scrubbers ( i personally used wire scrubbers,the one you use for washing dishes ) For the diaphram, you may use sheets like foam sheet or something like that....

hope you do your project well :)
What to do

Use the scissors to remove the neck of one balloon. ...Place one end of the straw into the other balloon. ...Make a hole through the plasticine. ...Place the balloon end of the straw into the bottle and use the clay to seal the opening of the bottle