Solar Sparkleball!

Step 5 Third Layer

In the space open at the top of the dome, insert the last four cups.  Fit them into the space at the same time.  Hold them with clothes pins.  Solder the cup bases to as many other cups as you can.  The more joints the sturdier the sparkleball.    When the half is complete,  you can reinforce it by melting joints wherever the cup rims touch. (See notches in photo)  You have half a sparkleball.