Weight Weenies

Hello weight weenies!
I want to get into the weenie world, and to do so I must have a very light bike. However, being a teenager, I don't have a limitless budget by any stretch. I hope to be able to build my own bike from scratch as I have experience in building bikes (I've assembled friends' road bikes) but if that is not possible a complete is possible. My current bike's dropout has snapped after a particularly nasty crash, so I need to start from scratch. Any suggestions?
P.S. If you're looking for a number moneywise I'm hoping to stay under $2700 for the custom, but preferences on light frame/seatpost. I can always upgrade wheels/tyres and groupsets, as you all know.

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FM066 / Sram mechanical, that's what I did at least.

Used supersix hi-mod ~900 USD
Custom aluminium wheels ~350 USD (bhs ultralite hubs, CN Spoke 424, alu rims)
Veloplugs & Vredestein latex inner tubes (or go tubeless)
SRAM RED crankset, cassette and shifters
SRAM Force derailleurs
EE Brakes
Carbon seatpost, handlebar, saddle from China
Extralite hyperstem O12
Deda traforato bartape
Keywin, xpedo or tuned speedplay pedals
KMC X11SL chain

~6100g

If you want a new frame: china carbon or planet x(?)
otherwise i think you should buy used.

Used Cannondale SS or Scott Addict and sand it down

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^^This, or check out my bike in my signature and replace the heavy Di2 with some lighter (and poss cheaper) mech groupset