How complex is the part? And, what is your background with (any) kind of drawing?
For a relatively simple part OpenSCAD doesn't require "drawing" skills as much as some math skills.
Tinkercad, Sketchup are both good starter programs for drawing with a mouse.
There are a lot of high end drawing programs that you can use, but most of them have significant cost with them.
The core thing to understand is that you are learning TECHNIQUES and the specific software you use will mature over time. Keep It Simple to start... draw some cubes and cylinders and figure out how to add/subtract them before you jump straight into forcing yourself to complex geometries.
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Standard disclaimer: the materials that Shapeways offers are for decorative purposes only. Anything that has the slightest physical stress to it might separate/shatter. Do not place yourself or others at risk of accident/bodily injury if a part fails.
Yes, a socket for a lamp might never be placed under such stresses. Just be careful what other parts you might select to design and offer to others.