This is a plugin for Nukkit, made in Java, which adds a command for you to use, to create a BlockBench model to edit and texture, this plugin can be useful for some stuff such as map selection. BlockBench isn't the most optimized, so from my testings, a 30x30x20 (Length, Width, Height) area seemed to be usable with a GTX 1650 GPU and an Intel i7-9750H CPU.
First, to create a block model, you will need to run the command /bbcreate ModelName minx,miny,minz maxx,maxy,maxz to create your model.
Once created, if everything goes successfully, you will be told that a new BlockBench model has been created under the BlockBenchModels folder.
After creating the model, you can double click it to open it, once opened, it will appear blank, that's since no block textures are implemented. You will need to select paint, then select the texture, then paint to your desire! A note about painting, each block has a 16x16 texture to paint in. Selecting edit, then the texture or a block, will show its area in the texture PNG, any paintings applied to one block, will apply for all of the same type!
The maximum amount of blocks in the texture can be 63