Hi,
I have made a few mats, mostly for coasters and trivets. One minor irritation is that when I finish them with a side splice I get a “lump” since the splice is just a bit thicker than the rest of the mat. Are there any handy tricks for avoiding this?
/P?r
Whip, or actually seize the end to the side of the neighbouring strand. Then it will only bulk up as much as the thickness of the twine you use. Pulled taught, it may even dig in enough not to bulk up at all.
I use something similar to a whipping, I tie a constrictor knot (ABOK 1249) around the end and a neighboring line. Sometimes I also will use a little superglue on the ends after the constrictor is tied.
Pat
I was hoping for a brilliant trick! 
I’ve done the “whip and lay next to” for decades, but visually a side-splice is less obvious if the mat is placed upside down.