Thanks for the comments on my site. I had no problems with the butt joints. The pygmy components seem to be either laser cut or cut with a cnc. The edges were very clean. Here's a butt joining process that worked for me.
1. Purchase a packet of clear overhead-projector mylar from the office supply store. Don't use the inkjet stuff, it will adhere to epoxy.
2. Cut out BOTH sides of the fiberglass cloth strips used to reinforce the butt joints.
3. Lay all the panels on the basement floor or garage floor (make sure it's fairly level), good side, or outer side DOWN and tape them into place on the floor, leaving the joints untaped.
4. Saturate one set of fiberglass joint strips and placed each on a sheet of mylar, placing each sheet under a joint, aligning it so it would contact the joint. Remember, good side down.
5. Check all the panel joints for alignment and tape them to the floor closer to each joint.
6. Now, epoxy the fiberglass strips to each joint that's face-up, place a clear sheet of mylar over the joint, put a piece of wood or paneling over the mylar, and finally weight down with a gallon jug filled with water, or other suitable weight.
* The result is a very clean reinforced inside joint, since it was face up.
* It doesn't matter if the outside taping isn't perfect, since I sand it off after stitching and gluing the panels together but before applying the saturation coat and fiberglass cloth.
* The process saves lots of time, gives you a strong and clean inner joint, and plenty of strength for assembly. You don't need that outer tape after it's all together. The fiberglass skin will be plenty strong by itself and your joint should be next to invisible.
* I've done this process with both System Three and Raka epoxy and had plenty of working time.