Like the guys said... You are better off buying some bar stock than making your own... The only reason I see making your own is if you want different colors that you can't buy or trying to make a different shape other than flat...
If you want to make your own, bubbles in the glass are a big no-no and will weaken the glass... In the pic I cannot tell if it is bubbles or fractures in the glass, or both...
For removing bubbles I would use a paddle roller like in the link below... Other rollers are not good for unidirectional glass and will get tangled... After you roll it out squeegee it flat... To keep the glass fibers oriented in one direction I would take a bunch of fibers and tape up the end so that you have a horse tail and work the fibers when wetting them out only in one direction... A hair comb can help for wetting out fibers... Don't comb to agressively and keep your comb on a good angle or you will pull and tangle fibers... Wet glass out on thick paper taped to the table or an old board... Lift and flip the horse tail multiple times until fully saturated then put into your form...Use multiple layers of horse tails to build up to the thickness you want.. After rolling out bubbles and excess resin, squeegee off the excess resin... Too much resin in the glass will make it weak...
If I was to make a bow with siyahs and laying up my own glass I might try laying up the working limb and siyahs all in one layup on a curved form so you would have reflex built in after you pull the part.. The siyahs may be a bit heavy though or you could experiment and add a wedge of wood between the layers of glass in the siyah area to lighten them...
I would stay away from pvc unless you are gonna build an all pvc bow.. You will find you will have adhesion issues when trying to adhere other things to it...
Hope this info helps...
https://grptools.com/products/laminating-rollers/paddle-roller/