23x20mm Aluminum tube. Could be any material as long as the walls are 1.5mm thick and matches the aforementioned dimensions. Length is up to you. The one in the render is 270mm.
3mm Aluminum Rods x2 100mm longs. To reinforce the main barrel. Rods run through the bottom like in the PPS one. Just mark and cut the lengths for the holes make sure to leave a space for the pivot pin.
M4x25mm Countersunk Bolt and M4 Nut
M6 x 35mm Steel Dowel Pin (Replaces old pin from old barrel, this sits flush with the handguard and acts as another point of contact for the handguard)