While I am not sure about Ferrocement in particular, I would say that you could have some success with cement in general if you have the
wire support. Also, if you have some other materials for interior support you may be able to lighten the project while still keeping it sturdy.
I assume that the
wire fencing that you might be able to get a hold of will be fairly light guage, similar to
chicken wire. If you can get anything heavier, like chain link fence (generally 16 ga if I remember) then it will be more difficult to shape but support your structure better.
If you can get some sort of posts (if you can get fencing, can you get fenc posts?), then you would want to create a starburst
pattern. To do this, you would connect the center of all the posts with
wire, beginning with a "+" and then a second set opposite on the z-axis (four posts required). You would then rough around these post ends the
globe shape. At this
point, you will need to make a hollow depression in the
ground maybe a 1/4 of the diameter deep. Set your skeleton in the depression and mix a small amount of concrete to fill this portion of the
globe, let it set. When this has cured, then you will rotate and do this again. You will want to make sure that the post is facing down each time so that it will bear the weight of the structure, especially as you start doing the extra sides. It will also likely require some exterior support as it gets bigger.
Don't worry about it being perfectly round at first. When you get all sections poured and set, then you will make more of a stucco with your cement (higher content of sand) which you will smooth out the structure and allow you to give the
globe some detail.
I understand that you will not be able to easily respond due to connectivity. When you do, try to fill in as much information as you can with any potential available materials, maybe even what part of Africa so that maybe we can make some assumptions.
Thank you for volunteering to help. I admire your effort.
