This is a parametric design of an electronic rain meter.

It measures precipitation, without the user having to empty the measurement glass every day. The clapper will fill with rain until it gets top-heavy and `claps over` to the other side. Then that side will fill...

The number of claps is a measure of total precipitation.

Print, assemble with 3mm filament, screws or coat hanger wire so that the clapper claps freely.

Counting claps A zero-programming and -soldering way of measuring claps is a bicycle computer. You need to find out the number of mm (or micrometer) rain/clap and enter this as wheel circumference, so instead of meters driven it shows mm rain on the odometer.

A millimeter of rain is actually quite a lot.

Mount (hot-glue?) a the magnet of the bicycle computer to the clapper. Mount the detector to the support, so the magnet passes every clap.

Calibrating Slowly pour a measured amount of water (100 ml or so) in the funnel while counting claps.

The openscad script will echo how many mm rain 100 ml is. The provided STL will, unscaled, have a Funnel surface of 78.54 cm² and adding 100 milliliter of water is thus equivalent to 12.73 mm precipitation. So, 12730/claps is the number you will enter in the bicycle computer.

More bicycle computer meteorology is coming with an anemometer.