Install Rust from here.
Run cargo install --git https://github.com/cool-mist/sol_chess to install the tool.
Run sol_chess --help to see the options.

Usage

Generate a puzzle

$ sol_chess -g -n 6
Generating a puzzle with 6 pieces with a maximum of 5 solutions
                Total attempts:     7
           Total pieces placed:    71
         Success pieces placed:    42
               Total time (ms):    69

               ♘  .  .  .

               ♙  .  ♖  .

               ♔  .  ♘  ♙

               .  .  .  .

Solve a puzzle

$ sol_chess -- --solve N...P.R.K.NP....
               ♘  .  .  .

               ♙  .  ♖  .

               ♔  .  ♘  ♙

               .  .  .  .


Found 3 solutions
1. Rc3 -> a3
2. Ra3 -> a4
3. Ra4 -> a2
4. Ra2 -> c2
5. Rc2 -> d2

Generate and solve a puzzle

$ sol_chess -g -n 6 --print
Generating a puzzle with 6 pieces with a maximum of 5 solutions
                Total attempts:     4
           Total pieces placed:    34
         Success pieces placed:    24
               Total time (ms):    38

               .  .  ♙  .

               ♕  .  .  ♘

               .  .  .  .

               ♗  ♖  .  ♘


Found 5 solutions
1. Rb1 -> a1
2. Ra1 -> d1
3. Rd1 -> d3
4. Qa3 -> d3
5. Qd3 -> c4

Heuristics of current algorithm

About 6-7 pieces on the board.
Select pieces to place based on its weight. 3. Eg: Queen is too powerful, so it has lower weightage. 4. Eg: Knights are confusing. More knights.