BLOCK: An Open-Source Bi-Stage MLLM Character-to-Skin Pipeline for Minecraft

We present $\mathbf{\text{BLOCK}}$, an open-source bi-stage character-to-skin pipeline that generates pixel-perfect Minecraft skins from arbitrary character concepts. BLOCK decomposes the problem into (i) a $\mathbf{\text{3D}}\mathbf{\text{preview}}\mathbf{\text{synthesis}}\mathbf{\text{stage}}$ driven by a large multimodal model (MLLM) with a carefully designed prompt-and-reference template, producing a consistent dual-panel (front/back) oblique-view Minecraft-style preview; and (ii) a $\mathbf{\text{skin}}\mathbf{\text{decoding}}\mathbf{\text{stage}}$ based on a fine-tuned FLUX.2 model that translates the preview into a skin atlas image. We further propose $\mathbf{\text{EvolveLoRA}}$, a progressive LoRA curriculum (text-to-image $\to$ image-to-image $\to$ preview-to-skin) that initializes each phase from the previous adapter to improve stability and efficiency. BLOCK is released with all prompt templates and fine-tuned weights to support reproducible character-to-skin generation.