Not sure if that's exactly right, but you know better.
I have an SD-SSG which I suppose should have the same size hingepins. They are 3mm inboard, and 2.5mm outboard. Now that I think of it it may actually be something weird like 2.4mm outboard.
Nevermind that though.
One option readily available is to go buy a decent tool with the right size shank (pin punch for instance, but can be a screwdriver, etc.). They are not going to be titanium, but tool steel if they're a good quality, and that's as strong as it gets (albeit heavier than titanium). Cut the shank to desired length and you have your hingepins. The advantage is they are precision ground to size.
Another idea is to use drill bits. Hard to find in that length since you can only use the round part of the shank, and a compounding problem is that only part of the shank is hardened, so it will bend past that point.
Looking for titanium is a good idea, but can take a while.
I have managed to find titanium rod eventually on ebay, but even though it was advertised as 3mm diameter in fact is was 3.14 for one of them and the other was 3.12mm. That is enogh to make the suspension arm articulation stiff. I had to sand them down and it's a PITA because you have to keep it round and consistent along the length.
Even aftermarket parts made by serious companies have this problem (i.e. they're a fraction too large). I bought OEM Traxxas suspension hingepins (Titanium) with this problem, I have bought Lunsford hingepins with this problem. There is nothing else you can do about it then but sand them down with a lot of patience.
Team Greasy Weasel
The best upgrade to any car is some driver skill.