Get yourself either 4' or 6' white melamine 3/4" shelf board from HD or Lowes.  Get the 16" wide one and rip 2 each 2" strips lengthwise.  Use tablesaw or straight edge with circular saw, it has to be straight cuts..  Screw and/or glue these to the underside like ribs to keep the top staight.  If you put them about an inch from either edge, you will have a good clamping edge for whatever.

Here is my wing and fuse jig.

This was sent to me when I asked the same question.

Thanks to everyone for all the great ideas. I hadn't thought about Steve's idea of CAing to glass. The wing jig will be fairly straight forward. The fuselage jig pieces require a slotted base to be adjustable. I have a 14" x 60" piece of commercial grade counter top that is 2 1/2 thick and hasn't warped in 15 years and should make a great base, but I haven't figured out how to cut slots in it. It may be better to do as Allan suggested and go with the 3/4" melamine. I could probably router slots in it.

Ty, thanks for the info about the booklet from Tom. I will certainly follow up on that.

Again, thanks to everyone for their input.

After everyone's great sugestions I coudn't let this rest until I passed on the information I got. I called Tom Morris to order the booklet that Ty suggested. While I had Tom on the phone I ask how he used his fuselage brackets. The answer was so simple that it is one of those things that makes you want to bang your head on the workbench.

Here is the Reader's Digest  version. Get the hard board like Allan suggested. Make a pattern from the top view of the plans. Take a piece of 1/8 balsa, plywood or etc. Draw the verticle line down the center of the 1/8 piece and the horizontal lines at the former locations. Use the pattern to cut the 1/8 piece, flipping it over to be sure it is accurate on both sides. Cut the 1/8 piece to make an exact template of the top view of the plans. Attach thw 1/8 template to the melamine/hardboard, centered & squared. Place the fuselage brackets at each side of the 1/8 template at the former locations and screw them to the board. Put the fuselage side pieces inside the brackets, put the engine crutch inside the fuselage side pieces and fit the formers inside for a tight fit. Basically build the fuselage inside the brackets on top of the template.

He went into more detail, but I think you will get the jest of it. He said you can make a perfect fuselage everytime for $15 for the brackets and a few bucks for the lumber.

Well, I do like Steve (I think) said.  I have a 3/8th" piece of tempered glass on my table so I tack glue the wing jig blocks in place with CA.  No screws, takes a minute or two to set everything up, and it works as good as anything.  Don't even need plans if you draw a wing on the glass with a Sharpie.

I do have a Byron Barker fuselage jig and would now never use anything else for building fuselages.  A very large nuclear device might not even harm it......  my great great great great great grand children will have it and it will still be in perfect shape (if anyone is around and building model airplanes at that time in the future).

Big Bear