You could put weights such as coins, lead, and other heavy materials in. Why I made the sand/clay jar for this model is you would not have to open the regular jar and spill what is inside. So, you can put sand, clay, steel BBs inside without a spill. The sand/clay lid fits snug with the sand/clay jar. REMEMBER TO PRINT THE SAND/CLAY JAR IN VASE MODE OR YOU ARE GOING TO BE LEFT WITH A CYLINDER. 

Print settings that work out for me:

• print in PETG
• 0.4, 0.6 nozzles work best
• print with 2 walls
• print with 15% infill
• if it says print in vase mode, PRINT IN VASE MODE

I also made some different sizes of jars, so I prefer measuring the height of your spool.