If you think you have the skills to machine an engine out of castings, making a displacement lubricator should be a piece of cake for you.
Jim...you may be right...lol...I machine brass all the time, however I almost never work with glass. The first pic is one I like but no sight window...second pic then second lubricator in from left has impressive widow but to large for Wilesco. I will have to give o-ring placement some thought for best glass seal. End of tube both ends seems most logical but I have not seen one dissassembled yet....
However, I have learned some years ago, just because you CAN...Does not mean you Should!...we all have a finite amount of free time and and sometime purchase of an product that Craftman have refined to high level IS the prefured method. I call it "choose your battles"