[HOWTO] How much space do I need to build for /e/?

You would need up to 140 GB for the source code files and about 250 GB empty on your hard disk to help with the build process.
A screen shot from a build server

Please note it is normal for build machines to be resource hungry …the more the RAM, Hard Disk empty space and the better the processor the faster will be the build.
Please cross check with the build specifications as given on the Android site here