I also made a stand for the blasting cabinet to get a comfortable working position. This is the reason for the elbow connector in the air line, so that it doesn't take room but goes down, as my workspace is very limited and getting pretty crowded with all the various stuff.
I welded the stand from 25 x 25 x 2 square steel tube, better known as "furniture tube" in here. I used a MIG welder because that was available and it is quick to use. I got the material from Rautasoini and it cost me about 20 EUR for the 9.6 meters of material and a cutting fee of 1.7 EUR, so quite cheap.
For welding the frame nice and square I bought a magnetic square from Biltema for 5.49 €. It provides 30 kg of magnetic pull and the 105 mm side length provides accuracy. I tested this little gadgets accuracy with a 400 mm machinist square and the magnetic square was truly a square. In retrospect I should have bought two or three of these to make the setups even more easy, but even with only one I could free my hands and got rid off of using clamps and got everything square in one go.
Once I had welded the frame I checked the diagonal lengths and found that there was 1 mm difference in 900 mm distance, so it was really good. The frame was a little bit twisted, as it rocked on the floor a little, but I fixed this by grinding about 0.5-1 mm off from one of the legs. This way the blasting cabinet sits on the stand without rocking during use. The floor side of the frame doesn't matter as the stand will have adjustable feet.
I used an air powered angle grinder to smooth the welds in all corners and then an angle sander on all surfaces to break the shiny metal so the paint sticks better. I wiped all the grinding dust with a rag and then used a clean rag and solvent to go through all surfaces to remove the last bits of dust and all the oil.
I had bought red oxide primer and black matte spray cans from Biltema for a total cost of about 10 EUR. I sprayed the primer on the frame in thin layers and with a help of a flashlight I inspected every surface that there were no metal to see and that the primer was smooth. I let the primer dry for half an hour and wiped the surfaces with a clean rag to remove the primer dust. I applied the black paint also in thin layers to get an even result, but run out of paint once I had the first layer, so I went and bought a second can of paint. This got me approximately two layers of paint and even surface, so good enough for me. I let the paint dry for two hours.
To give the stand good stability and finish I bought four plastic caps that were intended for this type of tube and had M10 nuts molded in them, so I could screw in the adjustable legs. The upper ends of the tubes I sealed off with similar end caps. All the caps I just whacked in with a rubber mallet and they fit snugly.
Once I got the stand home, I moved it to the correct place, adjusted the feet for level and stability and lifted the blasting cabinet on top of the stand. Fit as it should, with about 2 mm of free space from the tubes to the corners of the blasting cabinet.
Last bit to get this stand finished is to buy a piece of film faced plywood, cut the corners and install it on the supports I welded halfway up the stand to act as a storage space.