Initially, we fit the door to the fuselage and made mental notes where we needed to trim. After a couple of hours of fitting the door, trimming, sanding and repeating we finally had a good fit. We drilled the hole for the door handle and screwed that on.The biggest problem we experienced was reinserting the hinge pin back in. We used lithium grease which helped but it was still a struggle. However, the door is on and the pin is in. I riveted the striker plate to the longeron at the door.