Here’s a modular rule I created that taps into the Expert Features’ ‘Custom Commands’ functionality. It adds “flash” capability to any device (or other smartapp) that would otherwise be limited to on/off. It uses a virtual switch (momentary button tile) as the trigger to a real switch (an Aeon microswitch, which has a hardware-based flash/strobe function), If the physical switch is already on, it does nothing.
There is “The Flasher” smartapp, which accomplishes basically the same thing, but I’ve found it to be highly unpredictable for short-duration flashing (i.e., I might get all, some, or none of the number of flashes selected, or have it flash but then never turn off). Maybe if The Flasher ran locally… but this rule works 100% of the time.