Okay, this is how I made a garter from simple materials which I found I already had in my studio. I used two types of grosgrain ribbon (this ribbon was recycled from a gift of beautiful cupcakes we got at our engagement party), but you could use any ribbon you like, so long as it is wide enough for the job. I also had this vintage shoe clip which I threaded on, but you could stitch on flowers, crochet, feathers, lace or anything else that takes your fancy.
I started with four pieces of ribbon- the three blue pieces are 25mm wide and the striped ribbon is 15mm (a total of 90mm, which created a final garter width of 35mm). You could use different widths of ribbon, in various combinations, so long as they added up to about 90mm. My ribbons were 800mm in length (I'm a size 8)- but you might like to measure your thigh circumference and have a guess at how much extra length to add for gathering. Remember it is always better to make it possibly longer and trim it.
Then lay one ribbon on the top of the other with about a 2mm overlap and carefully top stitch your ribbons together. Check each time that you haven't missed any spots and re-do them if you have.
You should have something that looks like this.
Then place your next piece of ribbon (which will become the back middle strip), right down on top of the pieces you have already sewn. Stitch very carefully down the length of the ribbon as close to the edge as possible. Then fold the whole thing in half, right side on the inside and stitch along the edge to create the long tube of your inside out garter. Use a safety pin to pull through and turn it the right way. I was able to just push mine through because of the slippery nature of the ribbon, but it will depend what ribbon you use.
You then need to top stitch a channel for the elastic to go through. Iron the garter flat (be careful of your iron setting if you are using synthetic ribbon), how you would like it to be seen from the top, then sew twice down the length in the middle of the garter, leaving enough room in between the rows of sewing to thread the elastic through. My elastic was 5mm and I sewed with a 10mm gap down the edges of my striped middle ribbon. Thread the elastic through with a safety pin. If you are threading anything on, like I did, this is the time to do it.
Then bring the ends of the elastic together and measure it around your leg to get the right fit and tension. Either sew or tie your elastic together (be sure it's secure!) and cut off any excess. You then need to hand stitch the end of the garter together, don't worry about neatness as this will soon be covered.
Then take a piece of ribbon 2 1/2 times the width of the garter and wrap it around the join (with the end inside the garter), folding under the end of the ribbon to keep it neat, hand stitch the ribbon in place. This is a good spot to sew on your adornments if you are using any.
And voila! Handmade garter from simple, recycled, everyday materials.