I had an aerosol that I use in the garden that is made from concentrate. The concentrate is powerful stuff, so no way I'd like to use stuff from the kitchen to measure it. The top to the aerosol sprayer is also very narrow.
So I designed this simple measuring cylinder. The wide top makes it easy to pour the concentrate into; the conical shape means I can clearly see when it has the right amount (indicated by the groove 2/3 of the way up). The spout helps to pour the concentrate into the aerosol sprayer.
It's currently designed for 15ml or 0.5oz. Of course, since printing processes vary, this won't be exact, but certainly good for garden work. I used Taulman t-glase to print it. The t-glase has two advantages: it's transparent, and prints are watertight (and also food safe!). In total, it uses about 7g of material, which costs about 65c.
The OpenSCAD isn't fully parametrized correctly. I haven't included equations to work out the height for a given volume, nor did I work out the maths of spout correctly.
Print using a transparent material, e.g. Taulman t-glase