What custom designs do you build near the beginning of the game? Here are a few I've tried:
1) Fast Colony ship
Slap an engine on a colony ship to get there faster.
2) Fast scout
Two engines and a basic life support tank gets there faster, but sees less. Good for locating planets.
3) Sensor tanker
Fill a cargo hull up to the gills with sensors. Slowly sweep around the frontiers.
The tradeoff is usually speed for cost near the beginning of the game. I usually rework some of the designs to include an extra engine.
--Brad