So I used a few and it was very easy, fast, and accurate to apply the putty. I use Tamiya Putty (Basic Type) which dries somewhat fast so I have to work fast.
Photo 1 shows all I need to do this. Photo 2 shows extracting the needle from the needle hub for a fine application of putty. Photo 3 shows cutting off the end of the barrel where the hub threads in, for a medium bead. Photo 4 shows the used (dried) syringe ready to toss out.
Cost for anyone that has these is free! Just be careful and dispose of per your local regulations.
Lew