A cheap, simple, adaptable accessory for holding binoculars or cameras steady is a bean bag. I've used one for many years.

A cloth bag half-full of beans, peas, rice, sand, stones, polystyrene balls (or combination of same) -- whatever's handy and does the job. Use it to cradle the binoculars against any solid support -- corner of a wall, pole, fence-post, tree etc. I can't see Jupiters four biggest moons if I hand-hold my 8x binoculars, but a bean bag used properly will hold my binoculars rigid so that I can see them.

Bean bags are excellent for trampers because the empty cloth bag can be carried and temporary stuffed with whatever is available.

It's hard to give precise directions that will suit everyone but some general guidelines are:

1) It's length should about the same as the greatest dimension of the object being held.

2) Width about two-thirds to three-quarters of the length.

3) Corners are best rounded, otherwise they have a habit of getting in the way when the binoculars are pressed into the bag.

4) Use both a natural-fibre material and a filling that are not slippery, and only half- to two-thirds fill the bag. It needs to be pliable enough to mould itself around uneven surfaces, but must hold its position once set. Don't use a plastic lining -- it's too slippery. Polystyrene filler may not be rigid enough.

5) Consider whether you need a simple and effective means of opening the bag -- either velcro or a sturdy zip.

The best way to find the right size and shape is to experiment with different sizes of zip-up plastic bag and different fillings, but keep in mind that their slipperiness will make them nowhere near as effective as a cloth bag.

I'm currently using a denim bag which, at 20 x 12 x 5 cm, is a little too big and doesn't need the 5 cm thickness. If I was to make another I'd try two pieces just over 12 x 15 cm with rounded corners.