I need to make 2.5, 5, 10 and 15 tablespoon measurements regularly. Even the shortcuts to those measurements are tedious (e.g. 10T = 1/2C + 2T). I figured that my 3D printer and I ought to do something about that.
Those specific measurement sizes probably aren't very useful to anyone but me, but I have included the OpenSCAD file, so if you need another size and aren't afraid to use OpenSCAD, go for it. Instructions for creating a measuring cups in this style of your own size are in "How I Designed This" below.
In addition to being able to measure the intended volume accurately, a label has been added to the top of the handle to identify the measured amount. The label is also customizable in OpenSCAD.
There are also small lip cutouts to prevent dribbling down the side of the cup when you pour and finger hole cutouts in the handles to make them easier to grip.
For cups that are 10 tablespoons and larger, you may (if your printer behaves like mine) need active cooling for the lower 25% of the model - the part where the sphere is curved slightly up, but is somewhat flat.
I printed in PLA and had issues with the edges of the overhangs on the sphere curling up until I added active cooling. If you do not have an active cooling system and this is a problem for you, you should be able to have a desk fan blow on the model after the first 1mm has printed and until the overhang decreases enough that the print is smooth. I would also suggest adding a small brim for larger measuring cups.
If you are planning on measuring liquids, i would recommend at least 3 shell layers.
OpenSCAD and some math
If you want to make a measuring cup of your own size, you will need to know the radius of a sphere that holds the measured volume. You can find volume by typing into Google, for example, "volume of 8 tablespoons in mm" Then:
Step 1. Do the math
V = (4/3) pi r^3
118294mm = 4.1888 * r^3
28240.5462mm = r^3
30.45mm = r
Step 2. Change the inputs to makeCup
makeCup( 30.45, "8T" );
Step 3. Adjust the label offset
Set the textOffsetDivisor value. 2.5 will probably work (or be close)
Step 3a. Optionally set extraOffset in makeHandle below to make the handle closer to or further away from the main cup
Step 5. Render
Step 6. Export to STL
Step 7. Slice
Step 8. Print
I would also recommend testing by printing the 5 tablespoon cup to see if your printer needs an additional offset for the multiplicationFactor variable.