This post has inspired me to do this on my own. How did you apply the plasti-dip to the handles of the model 3?
I'm not the OP but I've dipped my own cars before and consider myself pretty good at it.
First, clean the handle and surrounding area with isopropyl alcohol. This will get rid of any fingerprint oils and other junk. Let it dry.
Next, tape off around the handle, leaving about an inch of exposed body panel (don't worry, when it's all dry, it's really easy to peel off the plastidip on the panel). Then tape sheets of newspaper to protect the larger area from overspray. Blue painter's tape works well here.
To get the sides of the handle, you're going to need to find something that acts as a shim to keep the handle sticking out. I usually just use a chop saw to cut a piece of scrap wood to size. Whatever you use, just wedge the handle so it can't retract, being careful not to block the handle from your spray. Some people only care about the side face of the handle. I prefer to get the top and bottom as well so the handle doesn't look unfinished when I pull on them.
Now, as for spraying technique: there's only one trick you need to know: don't just hold down the nozzle and go back and forth. By doing this, you create thick spots where you change directions. You spray in a single direction in a straight line then take your finger off the nozzle. Then go the other way doing the same thing. This will give you so much better control in terms of applying light coats.
First pass should give you around 50% coverage, meaning you can still see chrome. That's ok, even if it looks mottled. Get all surfaces covered using the finger lift at each direction change. Wait 5 min for it to dry (a bit longer if it's really cold).
2nd pass should pretty much get you 100% coverage - no chrome showing. Thinner coats are better. If it looks wet/shiny, that's thick enough. Try not to spray over areas that look shiny. Let dry for 5-10 min.
3rd pass: don't skip this coat even if it looks like you got good coverage over the chrome on pass 2. You ideally want to build up the plastidip so it's thick. Thicker the better; it will be more durable to scuffing/scratching, more resistant to weathering, and possibly most importantly: easy to remove if/when you decide to remove it. Again spray till you see wet/shiny sheen.
4th pass and beyond: I'd say you don't need more than 5 or 6 coats. In many cases 3 coats is plenty; it's just that everyone's definition of a thin coat is different, so to be safe, go with 5 or 6 coats. On every pass you should not neglect the body panel around the handle. Keep it as thick as the handle. This will make it much easier to remove when you're ready to unmask and peel excess.
If your shim blocked part of the handle, you'll want to move it a bit on the 2nd and 3rd passes so that the bald spots get coverage.
Wait 30 min for some extra drying, and now you're ready to remove your tape and newspaper. Peeling off plastidip is really fun. It's like a thin film of rubber, and maybe it's just me, but it's pretty fun to peel off and watch it tear perfectly at seams.
This same process applies to badges and other chrome pieces on body panels. Trim around the windows requires a bit more precision taping but other than that, the spraying application is the same.
I learned by surfing youtube, watching videos like this. Pretty easy if you're a bit handy.