If you want to build your own dummy load, then it seems to fail first because of the offered resistors. 50 Ω resistors with the necessary power are require large heat sink. Take therefore simply different resistors! Remind you of the Ohm's law and the parallel and/or series connection of resistors. In each good electronic shop you can buy non-inductive resistors for 0.25 or 0.5 W. In some stores also such for 1 or 2 W. Resistors made from carbon or metal oxid are good usuable. You can reread a few possible combinations on this webpage. If you solder this resistors to a suitable plug, then you receive a outstanding dummy load. In addition, you can solder SMD resistances on a PCB. No borders are set to your fantasy!
 
2 × 100 Ω/0,25 W = 50 Ω/0,5 W
2 × 100 Ω/0,5 W = 50 Ω/1 W
2 × 100 Ω/1 W = 50 Ω/2 W
2 × 100 Ω/2 W = 50 Ω/4 W
 
8 × 100 Ω/0,25 W = 50 Ω/2 W
8 × 100 Ω/0,5 W = 50 Ω/4 W
8 × 100 Ω/1 W = 50 Ω/8 W
8 × 100 Ω/2 W = 50 Ω/16 W
18 × 100 Ω/0,25 W = 50 Ω/4,5 W
18 × 100 Ω/0,5 W = 50 Ω/9 W
18 × 100 Ω/1 W = 50 Ω/18 W
18 × 100 Ω/2 W = 50 Ω/36 W
3 × 150 Ω/0,25 W = 50 Ω/0,75 W
3 × 150 Ω/0,5 W = 50 Ω/1,5 W
3 × 150 Ω/1 W = 50 Ω/3 W
3 × 150 Ω/2 W = 50 Ω/6 W
 
12 × 100 Ω/0,25 W = 50 Ω/3 W
12 × 100 Ω/0,5 W = 50 Ω/6 W
12 × 100 Ω/1 W = 50 Ω/12 W
12 × 100 Ω/2 W = 50 Ω/24 W
20 × 1000 Ω/0,25 W = 50 Ω/5 W
20 × 1000 Ω/0,5 W = 50 Ω/10 W
20 × 1000 Ω/1 W = 50 Ω/20 W
20 × 1000 Ω/2 W = 50 Ω/40 W
5 × 10 Ω/0,25 W = 50 Ω/1,25 W
5 × 10 Ω/0,5 W = 50 Ω/2,5 W
5 × 10 Ω/1 W = 50 Ω/5 W
5 × 10 Ω/2 W = 50 Ω/10 W
 
Note: In some pictures you can see a doted line. You can insert this connection or not. The function is the same.