In this study. we propose CoR-SketchAR. an augmented reality (AR) environment authoring tool that uses dry-erase markers for real-time collaboration among users. The most important requirement for multi-user collaboration in an AR environment is that the 3D virtual object must be placed at a specific location and can be easily changed by multiple users. https://macorners.shop/product-category/acrylic-first-day-of-school-sign/