Cubik Studio

You can use the whole 3x3x3 blocks, but the limits are -16 to +32.

You'll just need to move your model around or resize it and then use the display settings for scale to resize it in game.

Im brain afk, what do you mean with limit ? Sorry but im pretty new to this ^^

The limits mean that Minecraft will not load models with one or more elements partially or totally outside the grid in Cubik Studio.