Counting allowance points to 100 is fine but it takes forever. For a more short-term reward we now have this three-step path to a trip for ice cream. The design is BrianStamile's Mmmmmmmm Ice Cream model on Thingiverse, sliced up with matching indentations and protrusions in Tinkercad.
STL file: http://www.geekhaus.com/makerhome/day34_icecream.stl
Tinkercad link: https://tinkercad.com/things/6WHQ8ngOojd-day-34-ice-cream-stackers
Settings: Afinia .3 default normal, with a total of 1 hour and 8 minutes of printing time for all three pieces.
Technical notes: The indentations and protrusions were made as truncated cones in order to need minimal to no support material. Thank goodness for Tinkercad, which makes it so very easy to take an existing model and slice it, add or remove things, or otherwise remix. Thank you Tinkercad!!