To import your old models you still have to have BDcraft Cubik Pro installed.
6 steps to get your old saves imported to CubikStudio:
- Open BDcraft Cubik Pro and go to File > Open
- Select the .bdc3D/.bdc file and hit Open
- Check if everything is fine with the model and navigate to File > Export
- Export the model as .json (.obj works too but it may loose information) and close BDcraft Cubik Pro
- Open up CubikStudio and go to File > Import
- Navigate to your .json file you exportet before and hit Open
I hope this helped you!. And maybe CubikStudio will be able to import the old files sometime.
Feel free to ask and give feedback