Step 3: Filling with stars/burst and closing
Next cut two pieces of tissue paper, one of them with a hole to go over the time fuse or spolette. Put the pieces in each hemispheres against the stars and fill tighly with burst charge to the rim. A bit of "booster", such as whistle mix or flash powder is added in the center of each hemisphere and spread loosely in the burst charge with fingers. Not much should be used, maximum 1g.
Quickly snap the two shell hemispheres together. This is not as hard as it sounds like, but if done too slowly, the stars or burst charge might rearrange or fall out, and the previous steps will need to be repeated. If the rim each paper hemisphere touch eachother at this point, the shell is underfilled. However if done correctly there should be a small gap of around 1 cm at equator. Place the shell on the stand time fuse-side down, and use a wooden dowel to gently hit the upper hemisphere on different places. The stars will then arrange inside the shell and hopefully the two hemispheres will reach eachother. Seal up around the equator with masking tape to close the shell temporarily. Also put a piece of masking tape around the end of the time fuse or spolette to protect it from being damaged during the next steps.