Reddit mentions of 50 Blue Parchment 65lb Cover Weight Paper 8.5 X 14 Inches Cardstock Colored Sheets Legal Size -Printable Old Parchment Semblance

Here's all the files you'll need.

For the paper, I just use standard 8.5x14" Legal paper. My printer has a duplexer, but it won't duplex legal, so I had to do a manual duplex (flipping the paper over by hand and printing everything again). The cover is 65lb Bristol Board and was manually duplexed as well.

My books have 10 pages in them, which is made by two sides of 5 sheets of paper. The pages print 2-up per page and they are cut down the middle long-ways, that way when you fold them in half, the score sheet appears on the front page and the notes page ends up on the back of the score sheet. 5 sheets of paper make two books. I have a paper cutter that can cut the full length of the legal sheet, but if you don't, you can simply use a straight edge and a razor blade, or if you have a regular paper cutter, you can just fold the pages in half on the short edge, then cut them in half on the long edge.

Once everything is stapled, I round the corners using a corner cutter. Here's a cheaper corner cutter, but it can't handle the whole book at once. I have both of those corner cutters, and the cheaper one comes in very handy for other projects I do.

In that link is both Trap and Skeet books. I have a doubles sheet, but I need to finish the cover. Once I get done with it, it'll be in that link as well.