by Phunguss  

New idea.  Lightweight, portable, super cheap.  How can we do that?  I thought about something as easy as corrugated cardboard.  Then I thought I needed something more weatherproof but still lightweight, which lead to coroplast (plastic corrugated sign material).  After looking into that, it seems it is difficult to get adhesives to work well with coroplast, so what else?  Maybe Foamcore (thin paper/cardboard sandwich with foam inside)?  Well, cheap made me go with 3/4" 4x8' pink foam from Home Depot for $17.

Pink Design

Here is one fourth.  I am currently trying to squeeze it all out from one sheet to create a 4x3 panel that should yield 2000 Watts.

Pink Quad

Pink Bowl

Cheap Parts

by Phunguss  

The concept is to make this entirely with hand tools (or even less).  To do that, materials have to be easily cut, modified, and connected.  So, the materials we will need are:

  • 3/4 inch 4x8 sheet of extruded styrofoam (Home Depot)
  • CoroPlast   for the bowl (Hobby store, maybe Walmart, probably Kinkos)
  • Aluminum Foil or reflective mylar
  • A utility knife or box cutter
  • Foam adhesive (Liquid Nails PL300 - Home Depot)
  • Plain Elmer's Glue or 3M spray adhesive

I'll work out a design and layout to cut the foam.  Then glue the ribs together to make the frame.  Add the Coroplast to the top to form the bowl, then use a low yield adhesive to attach the aluminum foil to the Coroplast.

CoroPlast Cover

Aluminum Foil

Shopping spree

by Phunguss  

Seems I could find Coroplast (corrugated plastic) online without any trouble.  But I could not find it in any stores.  Lowes finally had some.  Grabbed their version of extruded foam insualtion, but it was not pink.  Who cares.

Foam and Coroplast


by Phunguss  

Requirements for this project are pretty minimal.  A utility knife to cut things, and some glue (pl300 is for foam insulation, caulk as general purpose glue to hold the Coroplast to the foam).


Designed it

by Phunguss  

Desgined a layout for the foam ribs... printed an 8.5x11 template and taped it together.  Then trimmed it and traced it onto the foam.  It's ready for cutting now.


foamy template

I like ribs

by Phunguss  

I cut the ribs with a standard utility knife.  I didn't hold the knife blade perfectly perpendicular to the cutting surface, so there are slight angles to the ribs... not a real problem, as this is all rather inaccurate to begin with.

Ribs one

It looks just like I thought it would.  I added some 'legs' to the ribs for further support.

Ribs 2

Shape the bowl

by Phunguss  

I also made a template for the triangles (long pizza slices) from Coroplast for the bottom of the bowl.


Yeah, it looks pretty close to the design above.