I usually make these kind of bloc’s without any lisp and my algorithm is very simple
1. Make a block
2. Bedit block
3. Make boundary closed polyline around block
4. Wipeout closed polyline around block
5. Draworder: select wipeout and send it to back
6. Close bedit with save
7. Wblock edited block
And that it!
I tried to automate this problem by lisp but not successful.
Please help me…