I only build with internal routing. I do non-sleeved routing throughout the frame.
Fully internal for everything besides flat mount bikes. For flat mount bikes I do internal through the front triangle and then external along the bottom of the chain stays for both the brake and derailleur.
I silver braze little laser cut .03” thick stainless reinforcements to the outside of the tube, then slot ~7x15mm ports with the mill. For the dropper I slot the bb from the down tube into the seat tube - with a bit of a notch sloted in the front of the seat tube.
The lack of places for cables to get caught inside the frame makes routing these bikes very quick and it can be done without magnets or any tools really. I provide them with foam tubes that slide over the hoses for a rattle free life.
Below is a dorky video of me running hoses and what not for one of my frames. (With some more words about why I do internal routing)
It took me under 5 min to route this one.
https://www.instagram.com/p/CgxcHXtPLFb/?igshid=MWI4MTIyMDE=
