FLUX 3 Image Klein Hands-On is CRAZY

Hands-on test of FLUX 3 Image Klein (5.6B open-weights image model from Black Forest Labs, released Oct 15 2026) on a rented RunPod A40 48 GB at $0.59/hr. What is in the video, all measured on that pod: - Text to image, upsampler on vs off, same prompt and seed - Image edit with one reference - Multi-reference generation (2 of 5 runs came out clean, both with seed 1) - Bounding-box layout - The gotcha: new diffusers builds the prompt upsampler into the pipeline and the first run crashes with "'NoneType' object has no attribute 'apply_chat_template'"; remove the block and run the upsampler yourself Numbers (A40 48 GB): generation step 9.3-10.6 s text to image, 20.6 s edit, 33.3 s multi-reference, 9.7 s layout. Peak memory 22.8 GB. Wall time in my Gradio app is longer with the upsampler on (71-140 s) because I swap the 18.8 GB upsampler and the image model between CPU and GPU. Session cost: about $0.65 of A40 time (3,947 s at $0.59/hr). Links: - Blog: https://bfl.ai/blog/flux-3-image-klein - Model: https://huggingface.co/black-forest-labs/flux-3-image-klein - Upsampler: https://huggingface.co/black-forest-labs/flux-3-image-klein-pup - License: FLUX Kommunity License (free under $5M yearly revenue) Get GPUs Runpod: https://get.runpod.io/pe48 Get Hostinger: https://www.hostg.xyz/SHJiu Coupon Code "PROMPT" 10% discount ## Chapters 0:00 Hook 0:11 What we will run 0:30 What FLUX 3 Image Klein is 0:53 The required prompt upsampler 1:08 RunPod A40 setup 1:26 Gated model and HF token 1:43 Install and download (37 GB) 1:57 Gotcha: the built-in upsampler crash 2:16 First test: 9.9 s per image 2:31 The Gradio app 2:46 Demo 1: text to image 3:11 Upsampler on vs off 3:30 Demo 2: image edit 3:47 Demo 3: multi-reference 4:05 Multi-reference: 2 of 5 runs clean 4:23 Demo 4: bounding-box layout 4:48 Timings 5:06 Cost and license 5:20 Wrap up 🔗 Connect with me: Email → [email protected] Ko-fi → https://ko-fi.com/promptengineer Patreon → https://www.patreon.com/PromptEngineer975 Book a Call → https://calendly.com/prompt-engineer48/call GitHub → https://github.com/PromptEngineer48 Twitter/X → https://twitter.com/prompt48 Website → https://promptengineer48.com/