its easy enough to make your own bow and arrows, and with practise you can make something exceptionally deadly!
but yes there are lots of things, the easiest is just training your throwing abilities, getting more powerful and accurate!
as for actual tools to do so, you can use anything as a potential weapon, even car keys, just put it in your fist like its a push knife, that'll do some damage!
you could fire catapults, slings, use a bit of stick as a spear thrower, or traditionally an atlatl
spears, homemade crossbows, etc. etc.
the possibilities are endless, essentially anything that can hit with some force will do, even if it simply makes an attacker recoil it'll buy you a few seconds, obviously the more damaging the better, shards of glass would cut too and afford you even more time to get away.
you could get a water pistol to fire something flammable and have a lit match after the nozzle but i honestly wouldnt recommend it at all, the pressure behind it is nothing like powerful enough, and if the water pistol's tank got eaten away by whatever chemical you use, it could result in a nasty situation.....vinegar might work though, although long term it would eat away the parts, but get some vinegar in your eye and it would definately hurt....alternatively you could do a homemade take on pepper spray, either using simple chilli powder or if you want something really powerful, grow yourself some dorset nagas!...sun dry it, crush it down to a fine powder, mix it till its properly dissolved in water, and shoot that....the chilli powder will irritate eyes quite alot, but the naga should have them crying and rolling around on the floor
...but i would take caution with any of those approaches myself.
the single best defensive tool you have though, is your own body. you can train it up and make yourself able to take down someone twice the size, if your interested in defence look into martial arts, cliche yes, but also very effective...personally im planning on taking up eskrima in the next year or so, the philipino martial art that revolves around knives, sticks, improvised weapons and simply damaging an opponent so badly they cannot fight anymore.