fishing spear

first you have to print the parts (A,Bx2,C), insert insert A on top of one of the tubes and insert C on top of the other aluminium tube.
Now take two nuts of length 30 mm and size 6 mm and insert insert B, now repeat for the other insert.
Now take one of the two inserts and inside the internal thread of the nuts, insert glue and then insert a 6mm threaded rod 15cm long.
Insert the two B-inserts into the two tube tops, one into one and one into the other.
Now take three 4mm diameter poles and insert them into the insert with three holes at the end (A), you have created the spear tips!
Finally, drill a hole in the aluminium tube in the vicinity of the insert hole (B) and insert a rope with knots at the end, 6 cm long, and insert the ends of an elastic gym band into the two knots, you have created the elastic propeller of the spear! its a fishing spear, similar to pole spear and it can be disassembled for easy transport

here you are a video ( where someone build a spear similar to mine) its not the same , but you can take as an example to understand the functioning of the spear (THE VIDEO ITS NOT MINE)