I don't know of a anything that transfers well but is not messy. I used to use Prussian Blue but one day I couldn't find my tube of Prussian Blue so I just used a candle and sooted the parts. This worked pretty well but the constant re-lighting of the candle was a pain. Leaving it lit just was not a good idea due to the dripping wax. Anyway, before I found my tube of Prussian Blue, I went to the Dollar store and found the cheapest tube of lipstick they had. The stuff worked great and it is all I use now. Sure it is a bit messy and the heavier you put it on the part that you are fitting the greater the mess. But, if you use it judiciously it is great stuff. No matter what you use, it is going to get in places you don't want it but it can be sanded off wood easily or washed off metal parts with a solvent. Just do not use a solvent to remove it from wood because you can cause it to soak into the wood and stain it. Wipe and sand or scrape it from wood. You can also use masking tape around the area where you are working to keep it off places where you don't want it.
If you will look at pictures that some very skilled rifle builders have posted on this forum of builds in progress, you will often see smears of soot, or whatever they are using to fit parts, all over their unfinished stock. But when you see the finished product, all of the smears are gone and the stock is beautiful. Actually, it just doesn't have to be all of that big of a problem.
