JOURNEYMAN wrote:A second builder can theoretically build a drill while the repeater is in the process of building.
Shouldn't be possible.
Buildables (and generally points in space) have both a current and an expected power supply. The current is what you see on the bar below the buildable and what leads to buildables powering down if power is too low. It includes influence from temporary sources such as the basilisk but ignores buildables that are powered down or in construction. The expected power supply doesn't take temporary influence into account but it does consider buildables that are in construction. It is used to determine whether a new buildable may be built. So when one of the builders starts constructing a buildable that will drain all the remaining power, the other builder would not be able to place another power-consuming buildable there.
To be precise, there is a short timeframe (500 ms) where both buildables could be placed, which is in between calculations of the (expected) power supply. However, once construction is finished one of the buildables would power down, so there isn't really an advantage.