Find supplier for square plastic profile extrusion with slot

I need to find 1-3 sources (distributors or manufacturers) for a square plastic profile extrusion similar to the FischerTechnik profile (see attached) but without the black plastic insert. We prefer to buy them in lengths of 1-5 meters per piece. The material could be hard nylon or another hard plastic. The profiles will be cut to size and screwed onto base boards to make an educational kit (see attached sketch) and then cards about 1.6mm thick will be slid into the slots of the profiles. The profiles shall be square and no more than 25mm on each side. The color is preferably grey. The profile does NOT need to look like the FischerTechnik profile, as long as it accomplishes the same thing (can be mounted to a plate and allows for cards to be slid in). PCB card guides are also acceptable but we have searched extensively for a design that will work in this configuration and we can't fine one. This is not a high-volume product so we do not want to pay for custom tooling. I am looking for commercially available, off-the-shelf plastic profiles. I also need to buy them in both low volume (1-10pcs) for development and prototyping, and later in higher volumes (100-1000pcs) for medium-volume production. These could be from two different suppliers (an online distributor, for example, and later directly from the manufacturer). An example of a manufacturer is Fibrolux (see [login to view URL]) but unfortunately I cannot use this profile as it is too large (40mm instead of 25mm, and the gap of 8mm is too wide for the 1.6mm cards).