I designed this spool holder in onshape. It was made to work with most 1kg spools but it should be strong enough to hold much heavier spools due to it having 4 screw holes in the bottom so you can screw into the piece of wood. You will most likely have to slide the holder on from the end because I don't think it will be flexible enough to bend over the wood. If you decide to print it (I hope you do) print it on its side. Supports are optional for some fillets and chamfers on the bottom but if your printer is awesome at doing sharp angles you might not have to use them. I'm going to mark that it doesn't need supports but it really depends on your printer. Thanks so much for this opportunity!

-Sam