Thin wire pen (for coil winding etc.)

Needed a way to apply a very thin wire <<1mm with a somehow controlled tension level, so I upgraded the well known design of solder pens by a simple fixture for a felt disc wire tension axle. Additional materials needed: Bearing HK0408 2pcs, which are being pressed into the hole 4mm axle (or anything straight from steel with 4mm diameter which you're capable to cut a thread onto). I assume you could resin print an axle as well, but not sure whether the thread would hold up to the forces or whether the bearing play would end up having everything jiggle around. End stoppers with screw for 4mm axle 2pcs. Suitable small polishing disc, which you cut in half to have two felt discs (if you use one for a Dremel, you'll want to cut through the hole with a 4mm wood screw a few times to open up the center hole) M4 nut, 2pcs M4 washer and a spring of suitable size and stiffness (I had one in my collectibles box, can't tell where that originally cam from). Alternatively you can buy a pack of disc springs with slightly above 4mm inner diameter and stack them to get the desired stiffness (google is your friend -> how to stack disc springs for a certain spring force curve) I had the bearings, axle and endstop laying around from an earlier project, but you'll likely find everything easily nowadays on amazon. How to use: Use any long hex bit in reverse in a power drill to wind the wire onto one of the spools. Feed the end of the wire through the drum slot around the axle between the two felt discs through the slot in the pen handle through the pen end hole hang a desired weight to the wire and adjust the spring tension until you're able to just so lift the weight with the pen.