I'm sure your lack of Autocad experience helps a lot. Little things drive me crazy, for instance in Autocad you have snap features you can set before you even start a line command so that you can snap entities exactly where you want them and it stays there...no guessing or magnified eyeballs necessary. Snaps to intersections, endpoints, midpoints, centers, quads of circle circumference, tangents in 2D, and snaps to faces, edges at the very least in 3d would prevent doing it over and over and over. In Design Spark there's some.....you get itty bitty circles old guys can barely see, and the mouse often won't stay still long enough to catch one....and the hold on it very limited. And so you miss a lot.
Then there is no "stretch command" to snap it in......thought there was in just a few modes where you can...... Once, I thought I found a stretch command, turned out was actually just moving both ends.....not a help when you want to stretch....so you erase the line and try again.....and again. That's irksome!
Sorry you're having hell with your bullet plate. Post a screen shot of the latest incarnation, and share the issues you've run into. sometimes two heads....can save time and effort.