I am thinking to buy a 3d printer but my budget hangs around 200 dollars, i am a student and need it for small non-comlex designs

Without any description of what you want to do with it, how big, how fast, what materials, want to upgrade it, etc, you could've just googled it. 
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nope,i just want somethng durabe and of rnough size to ringt rasberry case,it wont bother me if its time consuming

Your not going to get much for the 200$ but as said, just google "3d printers under 250$" for example. creality, anycubic etc all have offerings in that category and all big enough for printing PI Cases etc. just dont expect a lot of features

I'm relatively new to 3D printing after buying a Bambulab A1 Mini last year, which has been brilliant.

It took about 20 minutes to set up and is very much plug-and-play. I've been using PLA for all my prints.. nothing more exotic than that, and have maybe had 2 failed prints in over 100.

For designing my own stuff I've used OnShape, and have loved how it all works in a browser, letting me jump from my laptop to my gaming PC to pick up where I left off.

Bambu Lab A1 or A1 mini. They were on sale few months back. Keep checking the website for future sale

Absolutely.. they're often on sale. Then you can get some filament without breaking the budget.

Taking notes...

There are a bunch of accessories you might want to consider getting.. I've blogged about it previously, so I'll paste in the list I collated:

• £3 Digital Caliper; essential for designing your own 3D models! I've recently upgraded to the Duratool steel caliper and really like it; Duratool steel caliper
• £5 3D Printer tool kit; there are multiple kits to choose from, but the trimming knife, scraper, cleaning needle, tweezers, and pliers deburring kit is more than enough IMO.
• £6 Storage box (216x165x95mm); sure you could print one, but they're cheap, well built & have foam inserts. Great for storing all your accessories.
• £3 Humidity sensors; for putting with your filament to warn you when the humidity is too high.
• £7 Amazon Vacuum Bags and Hand Pump; for storing your filament away from moisture.
• £3 Desiccant; orange reusable silica gel beads for keeping moisture away from your filament in storage. Allow 50g per spool. In v.sunny weather you can even dry them outdoors.
• £50 Ikea Air purifier; in my tests it does a good job filtering PM2.5 particles. New filters are £5 each.
• £6 Dust Cover; There are times that you won’t be using your 3D printer for a while, so a dust cover is a good investment for the A1 Mini (45x45x48cm).