Materials required
Blackout cloth 1.5 m
Any light colored or patterned material - 1.5 m
it's better to have both these cloths of the same widths and over 140 cm.
(At Fabricland all measurements are in metric, so bear with me, I am going to switch to imperial in a moment).
Elastic - 1 cm wide long to fit snugly on rear standard
Velcro - the kind that sticks on to fabric or a zipper if you are real handy with a sewing machine

I looked at the BTZS dark cloths and decided to "use" their design. I did not want a generic dark cloth, as i felt that theirs was too bulky.

1. Measure the circumference of the back if the camera. Mine was 28 inces, I added 4 more inches for roominess, and added 1 more inch for seams.

2. Fold both fabrics lengthwise. I used only about 40 +2 inches of both as I am a small person. In hindsight I should have bought only 1.25 m of each.

Make sure to cut out the triangular pieces from both the cover and liner. Stich together.
Overstich to make it look nice.

On the shorter side leave a 1.5 inch allowance on the cover fabric to fold over and stitch the channel (?) for the elastic. Same allowance on the longer side as hemming is less bulkier.

After stitching and folding over for the channel it should look like this:

Stitch sides together for about 15 inches. Not stitching sides together, stitch cover and lining together for the remaining length. This is the "underside" of the dark cloth.

Fold over the cover fabric on the liner and hem.

Run elastic through the channel and check on camera to see if it fits snugly.

I have not yet attached the velcro, as I am thinking about putting in a zipper instead. I find velcro irritating.

This how it looks on the camera:

I spent about $20 and 2 hours on this. But I have to tell you that sewing is my other hobby... ;-)