You can't physically make it coarser. You would have to put in extensions to make it thicker or fake it with a volumising shampoo and conditioner.
You Grow It. or use hair extensions
Depending on the type of fabric used to make the hair extensions, you may or may not be able to dye them. Consult the manufacturer of your hair extensions to answer this question.
The type of hair extensions you are referring to are all natural hair extensions that don't damage your hair.These hair extensions remain attached to your natural hair using either a small not,weft, or beads that are undetectable.Hair extensions do not in themselves make your hair grow,but instead give your hair more time to rest and grow.Hair extensions are either someone else's hair or fake hair that has been attached to your own hair by one of many methods to make your hair look longer and/or thicker. If extensions aren't done right, they can leave you with really thin damaged hair . If you plan on getting extensions, make sure it's done by someone who knows what they're doing.More info can be found in the below link.
You Grow It. or use hair extensions
There are some risks with using hair extensions on thin hair. As follows: If you hair is too fine, you cannot afford to damage your hair even by a little. So Clip in hair extensions might be your best option. If your hair is very thin, going out on a windy day might expose your extensions and cause embarrassment. You hair will not be suitable to all types of extensions. You need to buy thin wefts which are delicate to handle and more prone to damage.
Hair extensions do not make your hair grow. Extensions are applied to your scalp which probably won't help your hair grow. I would probably work with your hair naturally keeping it conditioned not in pony tails, buns, braids all the time and eating the right things to help your hair grow.
Any method of attachment is fine & will be undetectable if you go to a stylist & use quality hair.
Yes, you can glue wig clips to regular weaving hair & make your own clip-in extensions.
Without a doubt it's a micro rings method,silicone lined or shrinkies I agree. I have fine hair, and I have had extensions several times, using a variety of different methods. I currently have micro rings, and they are great for any hair texture because they are so fine, almost imperceptible. That said, with fine hair you must be very careful. All methods of hair extensions attach a large quantity of extension hair to a relatively small amount of your own hair. Even if the individual extensions are small, as they are with micro rings, you have an unnatural amount of weight added to your own hair. This can result in your own hair being pulled out as a result. You will always hear that 'hair extensions are damaging'. An HONEST stylist will admit that this is true, in all cases, and this is why.
You can't do it naturally. But, you can get extensions to make your hair look thick.
It is not recommended that you use chemicals in attempt to lengthen your hair; you can, however, temporarily make your hair longer with clip-in, sewn in, or bonded hair extensions.