Combine lemons, juice, vinegar and cucumbers in food processor. Chop until desired texture. I chop mine until it resembles a milkshake like texture. Larger chunks would be pretty to. This is a personal decision. You should have about four cups of this mixture. Put this in a large pot and bring to a rolling boil. Add pectin and return to a full boil for about a minute and a half. Add sugar and return to boil once again. Put in properly prepared jars and process in a boiling water canner for appropriate amount of time for altitude. For me it is 10 minutes.