Water timer

Simple hemisphere can be good resource for STEM activity. 

It deals with measurement of time. 

Ancient Indians relied on this instrument to keep track of time during the day as well as night. 

I have uploaded STL files with different combinations. Hole size is 3mm for all.

Diameter in mm and approximate weight of printed part in gram is in the name of the file.

Try printing the ones and decide the duration. You can add weight to play around with time.

Material : PLA

infill : 10 percent

wall thickness : 1.2 mm

Support : No

Here is the reference video for the activity