Vent duct adapter- 4" to rectangular

If it helps one person, it's worth it. I received an in-line duct fan for Christmas. Our upstairs has poor heating/cooling because the furnace fan doesn't have enough pressure to send it upstairs at a decent CFM. I found that I have a weird ancient/odd sized rectangular duct that needed to be converted to the fan's 4" circular connection. The rectangular side of the model is designed to slide into the duct a good ways for a better seal. I found that I didn't even need caulk. The ID of the circular side is 98mm. Also, when printing the model, I ran out of white and finished it in black. This can be printed on an X1C if you slice it as seen in the picture. H2 users will be able to print the object as a whole. Unfortunately I do not own an H2 series printer, but I will share the X1C 3mf file. Use JB Weld Plastic bonding epoxy to join the two pieces together, works really good. If you create an on-shape free account, you can modify the model parametrically here:https://