Yea try as i might i couldn’t find 25mm pipe. I ended up using 25.2mm chrome tube from bunnings. ( shower curtain rods) Its was a bit tight on the corner posts. i happened to have a 25.4 mm drill bit so i used that to open it up a bit( another way i sorted out the clearance problems was heating the tube up with a propane torch a touch…. what it worked….). If you use larger tube you will need to print the 25.4 mm feet as well they wont stretch. Someone on thingverse has drawn them already. As for the slides they seem to handle the extra diameter ok. Do as vicious says and don’t do anything up tight until its all together. You’ll work it out.