Does your enlarger head rotate? There is double-sided masking tape but test it to see if it damages the paper when removing it. If a border is okay drafting tape which is similar to masking tape but not as sticky might work. Having the paper flat against the wall is critical. You will also need to know exactly where to place it and to first have apiece on the wall to compose and focus. 2F/2F has a much better way.

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