Georgis Rose.
Thank you for your post. It is wonderful that a designer has taken the trouble to ask their potential customers what they want.
These are a few thoughts for what they are worth.
The first consideration is that the male and female bodys are, naturally, a different shape.
Males need to enhance their waist and hips. So, high waist bands are a start. These can be enhanced with some discrete padding to pull out the skirt at the hips.
Equally for trousers. Something that bulges out at the hips, perhaps with some gentle padding, possibly for a few cm. Also, to think about the shape of the groin.
The bust will need to be higher than clevage. Many MtFs have developed breasts but those that haven't may need to conceil what they use. However, it shouldn't really be too high.
The shoulders will need to appear sloped. Male shoulders tend to be wide and flat. Padding is a problem here as it can look really naff, almost Dallas (TV program).
The neck is a problem, not just the adams appale but the general angles. A collar will need to be discrete though.
Colours are a matter of personal taste. I like plain colours, whites especially.
For my own part, I don't like showey shoes. But a small heel does improve posture and make the feet appear smaller. Personally, I like good quality leather, brown, perhaps patent black. Round toes. Perhaps a small buckle.
As an MtF, my knowledge of the problems facing FtMs are limited and what I've learnt here is most of it.
But the main concerns are, shoulders which might appear to improve width, perhaps also the top of the back. Ftms seem to be quite happy with strapping their chests, but some consideration to this would be helpful.
The waist and hips are the principal concern. Pulling in the buttocks while leaving plenty of room for the front to be packed out.
Shoes need to enhance the expanse of the foot and widen the gaite. Hard heels would seem to be a consideration.
I've noticed, from most of the pictures posted here by FtMs that they seem to prefer some degree of attraction. Designs or splashes on the front seem to be popular.
Hope this is what you are looking for.
