I would use plastic extruded rod. I would stay away from acrylic as it will be easily attacked by solvents / chemicals. I would use either nylon as it is very chemically resistant and readily available. You can use an unfilled nylon or if you want a material with higher tensile you can use a glass filled nylon. It is available in different diameters and it can easily be machined down to whatever diameter you desire. You can also radius or chamfer the end as desired. McMaster Carr would have it in stock.