4-20ma Or 1-100 Ohms Variable Resistor Needed To Buy

Hi all,

I need an input to simulate a project.

It should be either a:
(i) 4-20mA variable source  or
(ii) 0 - 10mV variable adaptor  or
(iii) 0 - 100 Ohm variable resistor

Anybody with idea of where I can buy such.

The product (finished circuit) should be able to vary in-between the above ranges.

Thanks a lot.