It would operate like a car indicator lever, but just be a normal panel mount:
- Hold part way to either side for momentary on, release to off
- Click through the halfway point to either side for on, click back to centre for off.
Is there such a thing?
It is usually the mechanics of the indicator stalk that provides the momentary and non momentary function. Are these of any use?
SPDT momentary or DPDT momentary.
Leo..
Wawa:
SPDT momentary or DPDT momentary.https://solarbotics.com/product/swt13/
Leo..
Thanks but that's (ON)-OFF-(ON) with no permanent ON on the outsides.
MarkDerbyshire:
It is usually the mechanics of the indicator stalk that provides the momentary and non momentary function.
Should add it's not actually to replace a steering column indicator switch. I want to be able to pulse an actuator but not necessarily click it on.
wilfredmedlin:
Thanks but that's (ON)-OFF-(ON) with no permanent ON on the outsides.Should add it's not actually to replace a steering column indicator switch. I want to be able to pulse an actuator but not necessarily click it on.
Use a DPDT centre off toggle ,but have a pair of momentary press buttons either side of it to use to jog.
Tom... 
wilfredmedlin:
Should add it's not actually to replace a steering column indicator switch. I want to be able to pulse an actuator but not necessarily click it on.
I gathered that. What I am saying is that it is the stalk mechanics that provides the momentary/non momentary action - not the switch itself
TomGeorge:
Use a DPDT centre off toggle ,but have a pair of momentary press buttons either side of it to use to jog.
Tom...
Actually probably would use 2x toggles, an ON OFF ON and an (ON) OFF (ON) in parallel.
MarkDerbyshire:
What I am saying is that it is the stalk mechanics that provides the momentary/non momentary action - not the switch itself
Could be aye.
Not saying that no one makes it, but never saw one in 55 years of electrical work. 
Maybe you could use an ON-OFF-ON momentary and add some 'long press' code to create the maintained feature?
dougp:
Maybe you could use an ON-OFF-ON momentary and add some 'long press' code to create the maintained feature?
Might try that, but it will return to OFF and still be running which is confusing operationally, and I'd have to come up with a way to turn it off, like a quick (ON) blip which is counterintuitive.
I'm leaning towards an ON OFF ON and an (ON) OFF (ON) in parallel.
Get a 5-position rotary switch. (Or a 12-position one with the internal stop set to make it 5 positions.)
Make the Arduino only issue one pulse if it's switched to the "pulse" position from the center off. It won't have the "return to center" function without some more mechanical bits. Switching from "fwd" to "fwd pulse" is ignored. File down the lumps which make the detents so that the "pulse" positions have a different detent feel to the "on" ones.