This is an old period 3 c/3 branching spaceship of mine that is relatively simple. When it was found it looked so unlikely to really be a spaceship.
x = 58, y = 42
14boboo$13boobooboo$12bobbobobbo$13bo5boo4boo$22booboo$22boo3bo$22boo
$$22boo$22boo$16boo4boo4boo$16booboo4booboo$10boo4bobboo4boobbo4boo$
10booboo4boo4boo4booboo$9bo3boo16boobbo4boo$13boo16boo4booboo$37boobbo
4boo$13boo22boo4booboo$13boo28boo3bo$7boo4boo4boo22boo$7booboo4booboo$
boo4bobboo4boobbo4boo16boo$booboo4boo4boo4booboo16boo$o3boo16boo3bo9b
oo4boo4boo$4boo16boo13booboo4booboo$31boo4bobboo4boobbo4boo$31booboo4b
oo4boo4booboo$30bo3boo16boo3bo$34boo16boo$$34boo$34boo$28boo4boo4boo$
28booboo4booboo$22boo4bobboo4boobbo4boo$22booboo4boo4boo4booboo$16boo
4bobboo16boobbo4boo$16booboo4boo16boo4booboo$10boo4bobboo28boo3bo$10b
ooboo4boo28boo$9bo3boo$13boo!
The base 25P3H1V0.2 ship which supports the branches has a nice spark at the back. The wasp is another small c/3 ship with a back spark which can also support the branches. Unfortunately, neither of these ships has a synthesis, and the two other c/3 ships which have been synthesised cannot support the branches. Even if the brain is finally synthesised, that also won't work.
So forgetting the base ship for now, the arms are rather simple. Can anyone find a reaction to extend an arm to make bigger spaceships? The fact the the ends are somewhat self-repairing might help.
A much harder challenge is to find a reaction to start another branch under an existing one. I think that there is no solution to that.
BCNU,
-dbell