The basic rotten bottom on the left is simple to produce and only requires the minimum of materials. Form a loop in the bottom of the trace and tie on the weak link length of line.
Tie the other end of the weak link to the eye of the weight.
Cut a small square of closed cell foam or a square of plastic from a milk carton approximately 15 x 15 mm. Push a 25mm panel pin through the centre of the plastic or foam.
To assemble the rig push the trace line loop through the eye of the weight and slip the panel pin through the loop. Tension the line using the trace and the panel pin will be retained between the loop and the eye of the weight only releasing in the water.
Just as easy to produce the clip rotten bottom requires either a shop bought clip or a home made one.
Tie the clip to the end of the trace then tie the weak link length to the clip. The weight is then tied to the other end of the weak link.
Prior to casting the lead is simply hooked onto the clip.
You need to ensure that the eye on the weight is large enough to allow the clip to release freely. If the eye is small attach a lead link then use a second clip on this and link the two clips together before casting.
Caution: Neither of these rigs are suitable for power casting.