I really like making bibs - they're quick, easy, take very little fabric, and customized ones make great gifts. Yes, you really can do this in about 20 minutes. Maybe not the very first time, but once you make one, they'll fly by! I really find the hardest part to be picking a fabric!
Firstly, take a bib that you'd like to clone and trace it on your fabric. Be sure to trace it about about 1/2" larger around the edges for a seam allowance. That way, when you sew it, it'll be the same size as the bib you're copying. If you trace it exactly, it'll be 1/2" smaller all around. Here is your chance to make any adjustments you'd like as you make this "pattern." Want it to be longer? Wider? Bigger neck hole? Give it wings over the shoulders? Just draw it in! To trace it, you can use almost anything - pencil, chalk, sharpie, etc. The line is going to be inside the bib, so you won't see it anyway. I used a blue quilting marker that I had on hand. It shows up really bright and actually disappears with water. Nifty. Do this on both pieces of fabric you're using for your bib.
Next, with right sides facing each other, sew around the edges with a 1/2" seam (remember how you left all that extra space when tracing?), leaving an opening to turn it inside right. Here's a "learned the hard way" tip: leave the opening somewhere on the bib that isn't curved. Trying to recreate that curve perfectly while finishing the seam is nearly impossible and it just ends up looking messy. With this bib, I left the opening along the bottom.
With the bib still inside out, snip into the curves being careful not to cut the stitching. This will allow the fabric to bend and lay flat when its turned right. With all your nice snips, finally turn the bib inside right.
After you've turned it inside right iron it flat, turning in the opening flaps so it all aligns with the edge of the bib. With a coordinating thread, sew around the bib close to the edge. This will close up the turning hole and strengthen the bib. You can do a straight or decorative stitch - its up to you.
The last step for your clone-a-bib is to add the velcro closure. You can purchase velcro in black or white and in various widths. For this, one inch wide velcro works just fine. You have two options with placing the velcro - you can just put two little pieces that connect and close the bib or you can put a small tab on one side and a longer strip on the other. The second option allows the bib to grow with the baby.
Either way you decide, place the velcro where you want it and sew it into place with a zig zag stitch. Its important to get a strong seam since it will be tugged on over and over as the bib is used. After you place the velcro, you're done! The bib can be worn, drooled on, spit up on, and abused as normal.