There's a number of different ways you can go about putting this pretty simple coffee table together. I actually put mine together in a different set of steps: I first built the top, then the leg sides, then added the top to leg sides, followed by trundle construction. But what happened is this table is highly dependent on the tabletop as the main structure, and I had some not quite straight tabletop boards. This created a ton of problems for me, so I wanted to present these plans in a different order to help alleviate issues for you.
If you have straight boards and a Kreg Jig, it may make the most sense to just build the tabletop, build the leg sides, the frame, and the trundle, and then put the pieces together.
Either way we go, let's build those sides first. Because 1x6 boards can be a little "off" and end up changing overall widths, cut the trim pieces to match the width of four 1x6s as shown above. Nail and glue on.
TIP: for pocket hole jig users, also join center of each 1x6 to neighboring 1x6 edge to edge.