Hey there,
 

For our mod we want to copy the minecraft blockChest code and create a proxy between it.
The idea would be that the player thinks he is interacting with a normal chest, while he is really interacting with our special chest.
 

 ModelLoader.setCustomStateMapper(ModBlocks.blockMinecoloniesChest, new StateMapperBase() {
            @Override
            protected ModelResourceLocation getModelResourceLocation(final IBlockState state)
            {
                return new ModelResourceLocation(ModItems.permTool.getRegistryName(), INVENTORY) ;
            }
        });
        itemModelMesher.register(Item.getItemFromBlock(ModBlocks.blockMinecoloniesChest), 0,
                new ModelResourceLocation(Blocks.CHEST.getRegistryName(), INVENTORY));

I used these two to register the renderer.

And I made a copy of the tileEntity and the block.

But, unfortunately, I'm not able to see the block in my inventory (the world block renders just fine)

Exception on loading:

 

Quote

[11:38:33] [Client thread/ERROR] [FML]: Exception loading model for variant minecolonies:blockChest#facing=east for blockstate "minecolonies:blockChest[facing=east]"
net.minecraftforge.client.model.ModelLoaderRegistry$LoaderException: Exception loading model minecolonies:blockChest#facing=east with loader VariantLoader.INSTANCE, skipping
    at net.minecraftforge.client.model.ModelLoaderRegistry.getModel(ModelLoaderRegistry.java:153) ~[ModelLoaderRegistry.class:?]
    at net.minecraftforge.client.model.ModelLoader.registerVariant(ModelLoader.java:241) ~[ModelLoader.class:?]
    at net.minecraft.client.renderer.block.model.ModelBakery.loadBlock(ModelBakery.java:145) ~[ModelBakery.class:?]
    at net.minecraftforge.client.model.ModelLoader.loadBlocks(ModelLoader.java:229) ~[ModelLoader.class:?]
    at net.minecraftforge.client.model.ModelLoader.setupModelRegistry(ModelLoader.java:146) ~[ModelLoader.class:?]
    at net.minecraft.client.renderer.block.model.ModelManager.onResourceManagerReload(ModelManager.java:28) [ModelManager.class:?]
    at net.minecraft.client.resources.SimpleReloadableResourceManager.notifyReloadListeners(SimpleReloadableResourceManager.java:132) [SimpleReloadableResourceManager.class:?]
    at net.minecraft.client.resources.SimpleReloadableResourceManager.reloadResources(SimpleReloadableResourceManager.java:113) [SimpleReloadableResourceManager.class:?]
    at net.minecraft.client.Minecraft.refreshResources(Minecraft.java:799) [Minecraft.class:?]
    at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:340) [FMLClientHandler.class:?]
    at net.minecraft.client.Minecraft.startGame(Minecraft.java:561) [Minecraft.class:?]
    at net.minecraft.client.Minecraft.run(Minecraft.java:386) [Minecraft.class:?]
    at net.minecraft.client.main.Main.main(Main.java:118) [Main.class:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_121]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_121]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_121]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_121]
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_121]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_121]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_121]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_121]
    at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:97) [start/:?]
    at GradleStart.main(GradleStart.java:26) [start/:?]
Caused by: net.minecraft.client.renderer.block.model.ModelBlockDefinition$MissingVariantException
    at net.minecraft.client.renderer.block.model.ModelBlockDefinition.getVariant(ModelBlockDefinition.java:78) ~[ModelBlockDefinition.class:?]
    at net.minecraftforge.client.model.ModelLoader$VariantLoader.loadModel(ModelLoader.java:1184) ~[ModelLoader$VariantLoader.class:?]
    at net.minecraftforge.client.model.ModelLoaderRegistry.getModel(ModelLoaderRegistry.java:149) ~[ModelLoaderRegistry.class:?]
    ... 24 more

 

Additionally:

 

public void readFromNBT(NBTTagCompound compound)
    {
        super.readFromNBT(compound);

when I call super.readFromNbt it does give me an exception:

 

Quote

[11:45:49] [Server thread/ERROR] [FML]: A TileEntity type com.minecolonies.coremod.tileentities.TileEntityMinecoloniesChest has throw an exception trying to write state. It will not persist. Report this to the mod author
java.lang.RuntimeException: class com.minecolonies.coremod.tileentities.TileEntityMinecoloniesChest is missing a mapping! This is a bug!
    at net.minecraft.tileentity.TileEntity.writeInternal(TileEntity.java:95) ~[TileEntity.class:?]
    at net.minecraft.tileentity.TileEntity.writeToNBT(TileEntity.java:86) ~[TileEntity.class:?]
    at net.minecraft.tileentity.TileEntityLockable.writeToNBT(TileEntityLockable.java:23) ~[TileEntityLockable.class:?]
    at net.minecraft.tileentity.TileEntityChest.writeToNBT(TileEntityChest.java:175) ~[TileEntityChest.class:?]
    at com.minecolonies.coremod.tileentities.TileEntityMinecoloniesChest.writeToNBT(TileEntityMinecoloniesChest.java:107) ~[TileEntityMinecoloniesChest.class:?]
    at net.minecraft.world.chunk.storage.AnvilChunkLoader.writeChunkToNBT(AnvilChunkLoader.java:409) [AnvilChunkLoader.class:?]
    at net.minecraft.world.chunk.storage.AnvilChunkLoader.saveChunk(AnvilChunkLoader.java:182) [AnvilChunkLoader.class:?]
    at net.minecraft.world.gen.ChunkProviderServer.saveChunkData(ChunkProviderServer.java:205) [ChunkProviderServer.class:?]
    at net.minecraft.world.gen.ChunkProviderServer.saveChunks(ChunkProviderServer.java:233) [ChunkProviderServer.class:?]
    at net.minecraft.world.WorldServer.saveAllChunks(WorldServer.java:1062) [WorldServer.class:?]
    at net.minecraft.server.MinecraftServer.saveAllWorlds(MinecraftServer.java:414) [MinecraftServer.class:?]
    at net.minecraft.server.integrated.IntegratedServer.saveAllWorlds(IntegratedServer.java:238) [IntegratedServer.class:?]
    at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:710) [MinecraftServer.class:?]
    at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:156) [IntegratedServer.class:?]
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:536) [MinecraftServer.class:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]
 

 

 

Problem №1. Chests don't have a normal inventory model. Their rendering is built-in. 

Problem №2. You need to register your TileEntity with GameRegistry::registerTileEntity

Problem №1. Chests don't have a normal inventory model. Their rendering is built-in. 
So how do I manage this?

You can create your own model that would seem just like a chest. I mean, a chest model isn't that complicated, it is a 14x14x14 cube with a 1x2x1 lock . 

There is a way to bind TileEntitySpecialRenderers to Item+meta pairs(ForgeHooksClient::registerTESRItemStack) but it is marked as deprecated and is commented as 'Will be removed as soon as possible', so I wouldn't use it.

I mean I could simply copy the blockState and model and texture of minecraft and use that.
But I wanted to avoid that.

I mean if the models and items are already there in minecraft why can't I use them.

You can't. There is no model or a blockstate file for a chest, because Mojang hardcoded the rendering of the chest into the game's code. See TileEntityItemStackRenderer::renderByItem. It literally checks if the block if the itemstack being rendered is a chest and renders it as a tile entity if it is

okay, I just remembered I can simply drop a normal chest. I won't need the chest item in the inventory.
I just have to replace the chest on placement.

Anyway, here:

 

 ModelLoader.setCustomStateMapper(ModBlocks.blockMinecoloniesChest, new StateMapperBase() {
            @Override
            protected ModelResourceLocation getModelResourceLocation(final IBlockState state)
            {
                return new ModelResourceLocation(ModItems.permTool.getRegistryName(), INVENTORY) ;
            }
        });

I have "inventory". I think that isn't completely right. How do I get the ModelResourceLocation for the correct block?

(It works already quite well, the only problem are the particle effects)

I also tried to use "normal". Rendering, animation all works fine for the chest. Only thing missing are really the particle effects.