Filament Splicer w/ both ends PTFE
thingiverse
I like having both ends with PTFE housing. If you measure out the full length + a tiny bit extra and cut at an angle you get a perfect mating that should get rid of most extra at the welding side. Not my prettiest print but it is functional. I would print at 100% in something heat tolerant like ASA (which the prusa mini does handle amazingly) or PETG.
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