Yay for Platonic solids! Platonic solids are polyhedral shapes made of regular, symmetrical shapes, and there are only 5 of them. If you play or love someone who plays tabletop RPGs, you're very familiar with them. They make up the dice for those games. Cubes and tetrahedrons are very easy to sew, especially if you start with a fabric that has tessellating squares or triangles. The above models were sewn using swatches from a new collection I have up at Spoonflower. Any square or triangle fabric will work, or you could do them in patchwork shapes pretty easily too with a few more seams.
I did these with hand stitching because of their size.
Sewing the tetrahedron-
A tetrahedron is the shape you might know as a 4 sided die, 4 equilateral triangles that form an almost pyramid like shape. It's the shape used in pyramid tea bags as well.
If you're making a large one with various fabrics, you'll cut 4 triangles at the right size plus seam allowances. If you're handstitching a little one like me, you'll cut out your fabric like this-
First, find your 4 triangles, you want a multi-directional design if there is a design in them, and you'll be cutting out a strip with 60 degree angles on the sides.
Add your seam allowance. For me, it was about 1/3 of an inch since they are hand stitched. Chalk in that line, or use a permanent marker, they will be inside the seam so it won't show.
See the arrow? That's where you start stitching. But you'll need to pin it first because the second seam can be kind of a pain. With the right sides facing each other, pin A to be, C to F and E to D on the corners and in the middle. It's going to look a bit screwy because of that odd direction seam, it will work though. Starting at the arrow, stitch the A-B seam, then the F-C seam, take out all the pins and turn it right side out. Stuff it as firmly as you prefer. I used polyfil to stuff mine. Then slip stitch that last seam to close.
If you're using separate triangles, you'll make a strip as shown above, then stitch that final seam as described, leaving a gap for turning, then slip stitching that closed after stuffing. Tie knot in thread, and bury the thread end in the finished shape.
Sewing the Cube-
This is a lot easier, especially for anyone who is a regular reader of my blog! Because it goes together a lot like a box but with closed seams.
In my fabric, the knotwork squares are set up on a diagonal, so finding my base shape looked kind of like this-
Add seam allowances, cut out including seam allowances and clip corners.
Now it's time to stitch it. This will be done in a couple stages because you'll need to knot off the thread and start sewing from a different place.
So starting on the inside corner: A-B, C-J, D-E, which brings you to the bottom corner of D-E. Knot off thread and cut. Then from the inside corner, G-H, I-F, knot off thread and cut. From the inside corner, L-M- turn right side out and stuff, then slip stitch K-N to close.
These can be used as ornaments, toys, a little bigger than my models, juggling balls.