Has anyone used/use one?
I have purchased a cheap one off eBay but wondering if people have had results from using one?
How long can you wear them at one time?
Personally I think they are a waste of time. As a lingerie, corset and shapewear enthusiast who follows a lot of people who wear, make or retail corsets and other shaping undergarments the consensus is that it really depends on what your ultimate goals are. A waist trainer such as what I think you may have got will give a slight reduction but as for any actual "waist training" it won't make a significant difference.
Waist training is actually pretty tough as far as body modifications go. To really do it safely and to get longer lasting results it needs patience, dedication, time, a skilled corsetier who will make the correct corset for your shape and your waist training goals so it costs money. You can't slap on any old corset as some are made to set measurements and proportions which won't be good for some. Sure it may be steel boned but if the construction is poorly done it will not get the right shape for you and thus you will find that too much pressure is applied in some parts or not enough in others.
If proper waist training sounds like it isn't something for you there's nothing wrong with shaping garments for a temporary effect while it is worn. I also recommend toning exercises to tighten the core; I find when I'm really in my gym routine this all tightens and my waist is more pronounced on it's own because my core is more toned. These muscles are essentially your own corset keeping your organs in place so toning really helps get some shape.
Depends on what results you're looking for my waist is about 8 inches smaller than my hips part of it is my natural figure part of it is due to me wearing corsets all through my teen years and afterwards. I do have those material waist trainers if that's what you mean I wear mine to keep me warm in winter and sometimes when I'm using my weighted hula hoop as can leave bruises.
They're great to wear under clothes or a nice dress for an evening out as well . keep you warm so won't need a big chunky coat to keep you warm have to carry about.
If its shape you want then its best to save up for good steel boned ones or similar . Also research waist training as it can damage you so please look into that if its something u want to do long term. I did worsen a few of my problems from doing severe waist training and it can be constricting for asthma sufferers.
I have a few basque tops as well I wear for shape as I don't wear corsets very often anymore. Basque style tops are like cheat corsets but a lot comfier.
Ordering online is what I did for a lot of mine but then I wanted properly fitted ones which you can get by your own measurements :)