Where you have your gauze tin I would run a thin piece of say flag tape like the surveyors put onto say a star picket so the tin sits on it with the tape forming a "U" then just pull the tab and up she comes rather than a tight squeeze with the fingers. Also the pine may need to have a dose of BLOicon/Mineral Turps mix so it is impervious to the ingress of moisture as it seems the width gap is fairly tight between the risers if they swell then it may be a bit tardy to get the blocks to slide but I commend you on the build looks really good.