Reddit mentions of Aputure Timer Camera Remote Control Shutter Cable 3N, for Nikon D90, D3100, D3200, D5000, D5100, D7000, Inexpensive Intervalometer for Time Lapse

I don't know if it has an intervalomter function built in (I'm a Canon guy), but just get one of these and take all of five minutes to read the manual. Super easy to use. Then take all of your images and throw 'em in to your favorite video editing software and go to town. Fairly simple, honestly.

I use this intervalometer with my D3200, it works pretty well. I can use it either as a remote shutter release (just press the button), or I can set it up as if I were doing a time lapse to take a series of photos without having to press the button each time. If you have the gear for it, you can also use it to take very long exposures - an equatorial mount with tracking for AP, or something like a stack of ND filters for daytime photography. You'd just set the camera on bulb mode, and set the intervalometer for something like a five minute exposure (30s is the longest my camera can do alone).

Would this work?

If you bought a wireless remote it not going to work on the D3100. You need a wired one to work correctly. This one will work and give you more options than the oem nikon one. https://www.amazon.com/dp/B003Y2YTEE/ref=cm_sw_r_awd_AGZPub1PB96F6

Is this a good intervelometer for my d3200? does anyone have any better suggestions

just this but at a much cheaper price

Thanks! Like connorirw said, a tripod and long shutter speed is a necessity. That image in particular was taken over a 4 hour period to track the star movement. It's possible to get an effect like this with an exposure close to that length in bulb mode, but I find it's better to make a composite with several images stacked. This reduces noise and allows for the removal of any bad frames(like planes flying through the shot, etc).

So I focused on the stars and used f3.5, ISO 500, with 30sec exposures being taken over and over for the 4 hours. There are modes on most(all?) DSLRs for continuous shooting, but I used an intervalometer to set it up. At Sunrise I took another image with the lake in focus at a narrower aperture to add after creating the startrails.

Then I began the processing. I used an application called Starstax to create the composite image, which I exported to photoshop to blend the foreground in. I set the foreground layer mode to lighten and played around with a gradient filter to ensure the trails stayed bright.
This was my first attempt blending a brighter foreground layer with startrails in this way. It was trickier than I initially thought, and I'm not completely happy with the result. I typically light paint the specific foreground subject I want to focus on, which makes the editing much easier.

Sorry for the long post, hope it helped.