As a tradesman I have to protect myself with safety boots but don't want to get mud on customers' carpets. Having tried disposable plastic shoe covers they lasted minutes before tearing so I made my own heavy duty washable reusable version.
Step 1: Fabric & Sizing
I suggest choosing a thick cotton which will last the distance as it is not an insignificant task making these, they may as well be decent.
I am a size 11uk and I needed 380mm X 440mm. In case you have another size, just allow 100mm more than the boot lengthwise and 250mm more than the width of the boot.
Step 2: Sewing Plan
Having made these before several times I think this is the best method.
Fold back 25mm of both long sides and iron a crease.
With that crease temporarily unfolded so the fabric is flat, fold in half good sides together along the long side.
Sew along both short edges roughly 10mm in from the cut edge to allow for fraying.
Flip the original crease back over and see this into a tunnel for the elastic around the opening making sure you only see one side at a time!! Leave about a 20mm gap to allow elastic to be added in the next step.
Step 3: Adding Elastic
Turn the cover right side out.
Pin a long safety pin through the end of some 8mm elastic and feed into the gap you left in the tunnel. Work the pin pulling the elastic all round the tunnel & out of the gap again.
Pull elastic tight enough to allow the boot in but keep the cover on the boot. Knot off the elastic and see up the gap.
You are done!