As my ficus is still in a plastic pot, no drip tray, I plan to repot it in spring, but I don't know what size pot to use, could I use a 10cm pot? Or would I need one around 13-18cm...

That depends on size of the tree, your care scedule and the development phase of the tree.

its about the size of the average mass produced ficus ginsengs you would find in a shop :' )

If you aim for refinement, go for a pot same height as the trunk and slightly smaller than the tree in leangth and depth. If you aim for development, go for a pot 2-4 times the trunk size and slightly bigger than the tree in leangth and with. If you aim for truck thickening, go for the biggest pot you have space for.

I am afraid I didn't understand much of that

I am sorry to hear. Maybe try a few times more?

I am sorry to hear. Maybe try a few times more?

Bonsai is about long term development. To pull it thrue you need to have a vision. The vision is your map. Now make a plan on how to get there. That is your steering wheel.

You do not provide any more information than that you have a "standard" size mallsai. You do not show us a picture and you are not telling us what is your vision or plan. Your question is like asking what wheels you need for your car, but not tell us what car it is or where you are going with it.

Without specified questions the answer needs to be general. Again, I am sorry it did not help you.

Ohhh, very sorry. This time i shall include my intentions and add a couple pictures.

I intend to thicken the trunk a little bit, so i plan to have a larger pot, and i have also planned a sacrifice branch, and I plan for it to grow bushier eventually. the pot it is in now is 12cm-ish, so maybe i could go for 14-15cm so it has more nutrients for a bit?

As said. For thicken the trunk go for the biggest pot you have space for.

Ginseng ficus is normally concidered a house plant, not a bonsai. But it is possible by advanced trunk carving to make it look like one. Check out nigel saunders on youtube how he has done to his.