Best way to make a resupply ship?

[Nitram Draw]

Depends on how far away from a resupply base you will be. The cheapest is to use an LC with max engines, bridge, life support, quarters and fill up the rest of the space with supply components. It will hold a few thousand supply points.
Solar panels are great for an attacking fleet but if you have a repair bay available a resupply pod is even better. Use it every turn and it will be repaired. You can add thousands of points per turn this way. You just have to remove the supply ship from the fleet to use it and the recombine it into the fleet to have the supply distributed at the end of the turn.