Hi @mizamook, welcome to the forum 
You might want to try some of the 3D printed options discussed here (there are various 3D printing services online / at libraries and makerspaces if you don’t have your own), or perhaps using stainless steel mesh or similar
On this specifically, if thruster efficiency is important you’ll likely want to do some testing to determine which approach has the least impact on flow characteristics. I would imagine fine wire mesh could have the lowest flow resistance, but it’s difficult to say for sure.