I'm using aem infinity and thinking about doing an Idle stop solenoid for warm up high idle that I can control to turn off at temp some thing like this
https://www.amazon.com/1972-1974-Corvette-Carburetor-Idle-Solenoid/dp/B00AYPBR1M/ref=pd_lpo_2?pd_rd_w=3N6vZ&content-id=amzn1.sym.116f529c-aa4d-4763-b2b6-4d614ec7dc00&pf_rd_p=116f529c-aa4d-4763-b2b6-4d614ec7dc00&pf_rd_r=GAXAND1PP7H3TMV07KG4&pd_rd_wg =Ccxoq&pd_rd_r=47aa5cb3-069c-4c74-b776-3120a5e316de&pd_rd_i=B00AYPBR1M&psc=1

Making it from aluminum was the idea I was going for. I just need some dimensions, although I suppose they aren’t all that critical.

For the one I made, based on research I did here:

Length: 15mm
Diameter: 15mm
Slot width: 3mm

It can be any length really, I chose 15mm to facilitate two set screws but you could do shorter and one set screw, but I don't see any benefit there...

Also, you can 3D print in aluminum- I just checked at shapeways and the cost is $35 for aluminum, $30 for bronze/steel, $25 for stainless steel, and $3,618.18 for platinum if that's how you roll.

Thanks Showdown; that’s the information I need.

so this thread revived my lust for experimentation :D and i have a bit more info.

and i dug out the PWM valve i bought years ago, it's a sort of cheap clone of a bosch BMW E36 2 wire PWM valve.
hooked it up to the start-up injector port, and protected the inlet of the valve with a simple moped airfilter.

12V fused on one side, F-idle wire going to the microsquirt. (which grounds it out at certain frequencies to make it do its thing)

i tested a lot of frequencies (blowing and sucking on the valve at first :D ) and settled on 31Hz giving the best idle control (tested it idling warm, and i can make it go up to 2500 rpm). Going from 100% duty cycle (fully open 2500 rpm) to about 45% duty cycle (closed 950 rpm).
Every valve will be different. I could not find specs on this valve, but above settings gave the best results for me.

Then i put in a cranking duty cycle curve and a warmup duty cycle curve, and over a couple of days adjusted it so i have pretty good startup rpm control. Haven't had any really cold starts (freezing) yet, but im' confident it will do fine in freezing temps. 5°C starts give me around 1500rpm, nicely winding down to 950rpm over the warmup cycle. The car is immediately driveable as well, no hunting, no stumbling, pretty much perfect for a 42 year old car.

Now i can basically start the car in any condition, and it starts warm for a couple of seconds on slightly elevated idle before settling down to normal idle. This i found is the best strategy for easy starts on my engine and the relatively crude temperature readings i get from the temp sensor on the timing chain cover. (don't really wanna tap the oil line for temp control, it is dry and don't wanna tempt the gods and have a leaking oil line)

So for the last couple of weeks, i haven't had to use the hand throttle anymore.

all this is with a tbitz kit, upgraded to microsquirt/EDIS with GSF crank trigger. Running MS2 extra 3.4.2.

when I added a hand throttle to my efi converted car, upon removal of the original handbrake mechanism, I was fortunate to find that the aluminium collar with lock nut, was already present on my throttle rod... (even though this car didnt come with a hand throttle orignally)