[Teaching Tech] is not alone in hating layer lines in 3D prints and also hates sanding. He recently tried Incredafill putty, a UV-curable putty that you can use to cover up lines in prints. Once covered and cured, you sand the putty smooth. You can see what he thought of the product in the video below.
As many people suggested in the video comments, you can pull the same trick with UV resin thickened with some other substance. We’ve even covered using diluted resin to get a similar effect. The putty has more of the appearance of hair cream or some kind of ointment, so it was easy to spread around with a gloved finger. A brush also worked. UV curing was done by a small flashlight or the handy sun. However, you’ll see later that he used a UV curing station and that works well if you have one.
Of course, even after applying the putty, you still have to sand. We are assuming the sanding is easier than trying to sand the actual layer lines smooth. On the other hand, the resin dust is probably pretty toxic, so there is a trade-off involved.
The results did look good. Of course, since there was still sanding involved, how good it looks will depend on your sanding tools, your technique, and — perhaps most importantly — your patience. Sanding can do a lot for 3D prints. We might not trust it completely with resin dust, but you could get rid of at least some of the dust with a downdraft table.