* Rhombiyurt build notes,  2018 Matt Brand
  + Panels: Dow Super TUFF-R rigid foam insulation (8'x4'x1"):
    - Available at Home Depot.  Picked out 20 that had minimal damage
      from the Roxbury site after finding the stock in unsatisfactory
      condition in Watertown and Somerville.
    - Contrary to store's online description, these are indeed foil
      faced on both sides, but on one side the foil is paper-backed
      and painted light blue with dark blue logos.  Acetone will
      remove the paint, but this is too messy to be worthwhile.  Takes
      spray paint well.
    - Seems lighter and possibly a tad more rigid than standard
      Thermasheath.  Foil is not as strong as Thermasheath HD.
    - Bought two 1/4" plywood boards to protectively sandwich the
      panels for transport and to use as work surfaces.
  + Cutting
    - Cutting the foam releases captive foam blowing gas.  Smells like
      a short-chain hydrocarbon, none of which are good for you.  Risk
      seems to be glossed over in MSDS
      https://www.dow.com/webapps/msds/ShowPDF.aspx?id=090003e8806f27a7
      Best to stand upwind of the foam when cutting it (outside).
    - The foam is impregnated with glass fibers.  Gloves recommended
      but not necessary.  Blades go dull fast.
    - Some boards are longer than 8' and have one rough edge that's
      slightly off-square.  Most are slightly wider than 4'.  Trimming
      to a 4'x8' rectangle is sometimes necessary.
    - Sometimes one long edge of the board is swollen, possibly from
      being stored standing on that edge.  The foam near this edge
      fights the knife, often forming tear-outs that need to be sawed
      before the knife can continue.
    - Olfa 18mm blades mounted on sliding rails worked beautifully.  Good
      precise cuts even when the blades went dull.  No mess.
    - Rough cuts can be filed but this releases lots of blowing agent
      and does make a mess.  Avoid.
    - Remember that 5 of the wall panels will face the other way
      (silver side in) and therefore need to be flipped over when
      (optionally) beveling their edges.
      - Also worth keeping this in mind when cutting doors & windows.
  + Taping
    - All non-foam surfaces wiped down with acetone to remove oils &
      handprints prior to taping.  Do this outside standing upwind of
      the stuff.
    - All edges taped with 2" foil tape prior to assembly.  Heavier
      gauge foil means sturdier panel edges.
    - Hinges taped with 6" bidirectional filament tape, both sides,
      then covered with overlapping strips of 4" foil tape.
      Thin gauge OK.
    - Used foil tapes rated for high-temperature applications so that the
      sun won't melt the adhesive.
    - Smoothing the tapes with a plastic epoxy spreader did a
      great job of pressure-activating the adhesive and making the
      tape lie flush.  A plastic spatula would also work well.
    - After smoothing the foil-edging, the panels were air tight; made
      pinprick holes to allow pressure equilibriation on the playa.
      Also good for eliminating taping bubbles.
  + Joints
    - Built one yurt with square edges and Z-flap tape hinges and one
      yurt with beveled edges and simple hinges.  Neither was all that
      easy.  Took some fine-tuning to get consistent bevels from the
      cutter, but these joints seem to be sturdier.
    - Prior to assembly, numbered corners on the interior sides of the
      panels as per the assembly diagram so that corners, edges,
      orientations are unambiguous during tape-up.  Remember: 5 wall
      panels will face silver side inwards!
    - Prior to taping each joint, tacked the edges together with 2-4
      small pieces of tape.  Used the tacking to pull the panels
      tightly together.
    - For the beveled yurt, it was easiest to first join
      interior-hinged panels in pairs, then connect all by outside
      joints (on the inside), then to tape the other side of every
      joint while leafing through the pile like a book.  To tape
      interior beveled joints, built a jig that holds the panels
      together at a slightly more than 36-degree angle.  To tape while
      leafing, used scrap material to build a podium to hold the panels
      level.
    - For the Z-flap yurt, panels were simply connected in sequence.
    - A simple way to make a Z-flap:
      1. Put tape on top of panel #1, so that 1" of the tape cantilevers
         out beyond the panel edge.
      2. Put panel #2 on top of panel #1, with edges lined up.
      3. Using tiny pieces of tape, tack the cantilevered tape up so that its
         non-sticky side is tight against  panel #2's edge.
      4. Put tape on top of panel #2, cantilevered out 1"-2" out
         beyond the edge.
      5. Fold tape #2 down so that it's sticky side adheres to the
         sticky side of tape #1.
      6. Practice on scrap before doing an edge that matters
    - Added velcro flaps to the seam edges of the bevel yurt, so no
      taping needed when deploying (setting up).
      1. Located each flap to dangle off the edge of the seam's upper panel so
         that the seam is shielded from rain.
      2. The flap consists of BiFi tape with inward-facing Velcro adhered
         to the overhang.
      3. The flap is then covered with aluminum tape.
      4. The mating velcro strip is glued to the outside of the seam's
         lower panel with barge glue (taking care not to breathe the solvent).
  + Packing
    - Made a custom box out of hard fiberboard that fit the folded yurt exactly.
    - Attached panels edge-to-edge by punching holes near the edge of
      each panel and putting in zip ties in figure-8 loops to make live hinges.
    - Worked well but required lots of zip ties.
    - After some rough handling, a few holes that were too close
      to the edges tore out.
    - Might use pegboard or 1/8" plywood in next iteration.
  + Test unpack & build: beveled rhombiyurt 
    - Was done solo in a light breeze; in higher winds, more people
      will clearly be necessary.  Helpful to have a lot of space.
    - Useful to practice first with a stiff paper model cut out from
      the build diagram and folded as per the packing plan.
    - To unfurl the folded rhombiyurt, stand the package on one of
      the simple edges and pull the wall panels out like an
      accordion, until every pair of wall sections is resting on its
      short edges, with the long edge tented like a roof.  Note that
      every other roof-like wall pair will need to flip over and
      invert hinge direction.
    - Identify the inside and ease the wall sections into a curve in
      that direction, helping the upside-down walls to flip.  
    - Once flipped, all the walls will stand up. Arrange the walls
      into a circle, with the remaining diamond panels hanging down
      outside.  
    - From the other end, unfold 5 panels, arrange them into a star,
      and tape seam #1 to make the (temporarily upside-down) roof.
    - Flip the entire roof over onto the walls and seat it on the
      horizontal diamond panels above the walls.  Jostle the wall
      panels to make all seams line up.  Tack the roof corners and then
      tape the remaining horizontal seams.  A step-stool helps.
    - Put a tarp inside or under the yurt, if desired, tape the tarp
      edges to the walls.  Interior diameter is roughly 12'.
  + Actual deployment: both rhombiyurts
    - Worked as expected.  Good to have a ~20'x50' space for unfurling.
    - Both yurts are quite sturdy and stiff; the beveled yurt is bombproof.
    - For the unbeveled yurt, a little extra taping was needed to
      stabilize some of the Z-flap edges.  Tacking was sufficient.
    - Much more pleasant inside than hexayurt, due to domed ceiling.
      Lots of room to walk around without bumping one's head.
  + Lessons
    - Precise cuts and joins early on make everything easier later.
    - Good jigs save time and prevent mistakes.
    - Don't assume raw materials are square.
    - Probably will recommend making that easy version of the yurt;
      -- 1' shorter so all seams are easily reachable on playa
      -- doesn't require butt-joining "orphan" pieces during construction
      -- folds to a perfect diamond (simplifies boxing, storing)
    - The beveled, velcro-ed rhombiyurt is very easy to deploy, but
      its industrial-strength velcro is too strong; opening the seams
      for breakdown is a bit of a struggle.
    - Used a broom and blower to dust off the panels before repacking.