Polyimide (PI) rod/tube can be considered, which has the advantages of high strength, low friction coefficient, high heat resistance and good chemical stability, and will not be deformed due to temperature changes, nor will it be easily broken like a glass rod. Polyimide round rod/pipe has high hardness and can meet your needs. However, due to its special properties such as high temperature processing, the price is relatively high.

In addition, the round glass rod with high hardness, wear resistance and corrosion resistance can also meet your needs, but the price is also relatively high. If your demand is not very high, you can consider PVC round bars/pipes, which are relatively cheap but have low hardness.

You need to choose according to the specific situation. If you need to order these materials, you'd better consult professional material suppliers or manufacturers before choosing them, so as to know the performance and price of various materials more accurately.