Can anyone suggest a 4 GPU build for a non-GPU budget of USD 1500 to 2000 (i.e., not including the cost of the 4 GPUs, which will vary depending on which GPU is

Can anyone suggest a 4 GPU build for a non-GPU budget of USD 1500 to 2000 (i.e., not including the cost of the 4 GPUs, which will vary depending on which GPU is chosen)? I will add to this the cost of 4 GPUs (like GTX 1080 Ti or higher).