For making parallel lines to edges.  Use compass lead size 2 mm.  A bit tight at first but loosens up after a few times.  Inspired by DSPIAE scribing tool.   

✏️ 3D Printed Parallel Line Edge Tracer – Adjustable with 2mm Lead

Precision marking just got smarter. This 3D printed parallel line tracer is designed to effortlessly draw straight, consistent lines at a set distance from any edge—perfect for scale model scribing, GunPLA, woodworking, leathercraft, model making, or technical drawing. With adjustable thumbscrews and a snug-fit lead holder, it’s the ultimate tool for clean, repeatable layout work.

🔩 Key Features:

• Edge-Guided Design: The tool hugs the edge of your workpiece, guiding the lead in a perfectly parallel path.
• Adjustable Offset: Dual thumbscrews allow you to fine-tune the marking distance from 5mm to 50mm (or more depending on your model), giving you full control over spacing.
• 2mm Lead Compatibility: Accepts standard 2mm drafting or compass lead, held securely in a friction-fit channel or collet-style clamp.
• Ergonomic Grip: Contoured body for comfortable handling and smooth tracing across surfaces.
• Non-Marring Base: Printed in smooth PLA or PETG with optional felt or TPU pads to protect delicate surfaces.

🛠️ Ideal For:

• Scale models and GunPLA builders 
• Cabinet makers marking consistent insets
• Leatherworkers tracing stitch lines
• Artists and designers creating parallel guides
• DIYers and makers who love precision