Step 1: Design

I have elected to build a working prototype from 2.2 oz.* woodland camouflage polyurethane coated ripstop nylon.  My selection of this fabric is based on two separate but equal criteria.

1. Cost. Outdoor Wilderness Fabrics rotates sale items every so many months.  I found this fabric for something like $3 per yard.  I purchased 3 yards.
2. Hike Aesthetic. Making a working prototype allows me to go to the bargain bin and not feel like I'm wasting my money on fabrics I wouldn't use in the backcountry.  I like for my intentions to be clear when I'm out for a few days solo.  If I'm hiking, then I want people to know that I'm hiking.  I do not want to be, even remotely, likened to a hunter.  Therefore, I will not take a camouflage piece of kit with me when I hike.  Like wise, the weight of the fabric wouldn't withstand the 4th step in Backpacking Light 101.  Withstanding cost 1.1 oz. silicone impregnated ripstop or SpinnTex, or Cuben would all be better picks weight wise.
   

I've been working out a few different designs with Sketchup.  Given the yardage at my disposal, I will be making a tapered tarp.  I have chosen to cut two halves, flip flop one side, and sew the pieces together along a 96" edge.  By cutting the pattern at 96" I will loose about an inch in total tarp length, but its a sacrifice I am willing to make for simplicity sake. 7' 11" is fine for this prototype.  Ron Bell (MLD) used the diagonal cut to pull off a poncho from SpinnTex that was pretty ingenious.  The diagonal cut allows maximum use of yardage with very little waste.  I'm standing on Ron's shoulders here.  Will Rietveld wrote a great review of the  MLD SpinnTex Pro Poncho Tarp for BPL.

Another Reason for a Prototype

Being that the fabric is a PU coated make, flipping one side to make this tarp is going to give it an... interesting look.  On one side the coating will be out, exposed on the exterior of the tarp when pitched.  The other side will place the coated side in, down, or protected from exterior conditions.  This will be an productive outcome of circumstance. Productive because as I use this proto. I will be able to examine which way, if any, is best to use PU coated ripstop.  Using this tarp will provide me a list of things to do different next time, or may debunk some accepted knowledge of this specific fabric.  We will see.

Along the same lines I will be testing two different techniques used to attach guyout points made of grosgrain ribbon.  One method is a double bar tack the other is a box stitch.  Both are used a attaching tieout points and for reenforcing the junction between the two materials.  More on this in the future.

On to cutting...

* fabrics are distinguished by weight per square yard.  One square yard of my selected fabric weighs approximately 2.2 oz.