These days there is a wide variety in plastic figures in 1/72. They come in different quality and prices but they all have moldlines/seams/flash along the places where the halves of the mold have met. The 'moldlines' or 'flash' is excess plastic that flowed in the space between the moldhalves (green shaded area):
I always find this very not good looking and thus it must be removed from the figures. Unfortunately most figures are made from poly-ethylene which is too soft to sand off with sanding paper. With some of the harder varieties of plastic the flash can be removed with a knife but quite some figures are made out of plastic so soft cleaning them op with a knife is almost impossible.
For figures made out of this soft plastic I tried melting of the flash with a hot needle. I place needle in a the handle of my hobby knife and hold it above a flame. When the needle is warm I move it over the moldseem fast and it melts to merge with the part of the figure.
Depending on the kind of plastic the needle can be placed best at 0,5 too 1 cm above the flame. Don't put the needle in de the flame, the needle will become too hot and ashes will precipitate on the needle making it black. Also be careful to place the flame and figures on a surface that can withstand some heat like plate!
I didn't come up with this idea myself but I've seen it on youtube, for a video demonstrating this technique click here or see below:
A demonstration by mr. "colonial20mmsoldiers":
I tried the technique on 4 sets of figures. It worked well on the soft plastic of the 'El-Cid infantry' from 'HaT' and the 'US Infantry Ardennes' from Revell. It also worked on a set from Streles but that plastic is quite hard and the needle needs to be quite hot so you're reheating the needle all the time. With Zvezda figures I had no success.