Hey! You can't directly copy custom forms between environments, but there are a couple ways to handle this:
SDF (SuiteCloud Development Framework) is the cleanest method - you can deploy custom forms as part of a bundle from sandbox to production. Requires some setup but handles dependencies well. Manual recreation is more common - screenshot the sandbox form layout and rebuild it in production. Tedious but straightforward. CSV export/import works for some form elements but not the full layout structure. Most teams go with manual recreation for one-off forms or SDF if you're doing regular deployments.