I am still using that cable that I soldered the crimp-connector onto. It has held up over more than 500 miles. I used a "red" crimp connector with the loop/eye on it, held by a pair of needle nose pliers as I soldered it in place (marked cable with a sharpie first). I clipped the loop off with cable cutters, but that could be used for other applications such as home-made levers. I had to file it quite a bit to get it to sink into the carburetor lever pivot. (What's the name for that?) I made it so it was pulled tight by the cable and does not move freely, but is pressed into place. I have taken it out a couple times with the pliers, for carb upgrades (boost bottle project), and it still fit tightly and stayed put.
One I made on another bike, from a brass tube that came from an ink pen, has also held up well, used with a v-brake lever. I heated the tube until all the ink burned off or dripped out, and assembled it similarly to the crimp connector one. It did not require much filing, and is held in place by cable tension.
For simply making cable ends to prevent fraying, and not to relay tension, you can crimp old spoke nipples onto the cables, or solder them on.