Starting layout: 4m × 3m. This is an illustrative design prompt; check furniture, equipment and internal clearances.
Start with the layout
Map the workbench, materials and circulation space. Check the size of anything that must pass through the doors.
Get the specification right
For music, acoustic treatment inside the room and sound isolation to neighbours are different jobs. Get specialist advice before deciding the wall and roof build-up.
Plan the details early
For painting or making, assess ventilation, dust, substances and clean-up needs. A sink introduces services and drainage questions.
Build a complete brief
Record internal dimensions, intended use, ventilation, services and access. Share the same brief with every supplier so quotes can be compared. Check planning and building-control requirements before committing to a particular height or footprint.