Catching up: I've been planning future projects for the Chertsey Museum classes:
Triangular box from this lot
Print
this template onto card (or onto paper and glue onto card), cut out all the pieces
Cut fabric about 1cm bigger than the card (I used one fabric for the 'inner' pieces, and another for the 'outer' pieces), and cut wadding the same size as the card for the pieces that need it.
Use masking tape or glue to tape fabric around the card (inc wadding where appropriate).
(You could tack the fabric and card together as with EPP)
I took these pieces with me to Jackie's last weekend, and worked on them . . .
Next:
Whip stitch the three inner rectangles (yellow in pic below) to create a triaglular pot, then join the base onto the pot (NB fabric *inside*on all 4 pieces).
Repeat with the outer (pink below) rectangles and triangle, with fabric out.
I found I preferred the look of a whip stitch where the external part of the stitch is perpendicular to the join, and the internal part is diagonal
Slide the inner pot into the outer pot. Whip stitch the top edges together around the top to keep them from moving
Whip stitch the inner lid triangle to the centre of the outer lid triangle. Whip stitch (from the inside) one edge of the lid to one edge of the top of the pot
Take a deep breath, put away your whips, and admire your box from all angles
