Legacy COBOL systems, which power critical applications in banking, healthcare, and government, are facing a steep decline in skilled COBOL developers and a lack of interactive learning tools for novices. While block-based and visual programming environments exist for programming languages such as C and Python, there are no such tools for legacy languages like COBOL. This paper presents COBMaker, a visual block-based programming interface that provides modular, drag-and-drop blocks for COBOL programming structures, organized in a playbook-style based on COBOL 85 grammar. COBMaker supports structured program construction, abstracts low-level syntax, and enables novice programmers with no prior COBOL experience to write and run COBOL programs directly through the web interface. Our evaluation, conducted with 24 novice programmers across five tasks, demonstrated that COBMaker reduced mental demand by 28%, effort by 55%, and frustration by 66%, while improving perceived performance by 39% compared to text-based COBOL programming. These findings demonstrate the potential of visual programming to lower the learning barrier associated with COBOL and provide insights for legacy language education. The tool demo video is available at https://youtu.be/XOgJ-9olNHg, and the tool and artifacts are at https://github.com/satish-pati/COBMaker.