Bitcoin Difficultly Increase

When the new Butterflylabs asic Platforms come out how far will the difficultly increase and will that be the end of bitcoin mining on the gpu

Well the difficulty will increase until no more coins can be mined.

The use of asic miners will drastically increase the difficulty very rapidly. But this also depends on how many of them go into use.

GPU mining is already pretty much dead (when trying to mine by yourself), so soon only asics will actually be able to generate coins.

Difficulty is a value that is adjusted every 2016 blocks mined.  The value increases or decreases in order to keep the total time between each successfully mined block at approximately 10 minutes.

How hard is it to make own ASIC chips for BTC mining ?

Well the term ASIC means "Application-Specific Intergrated Circuit", so if you have your own chip fab and the know how. Easy. However without these things, you'd be dealing with massive amounts of large circuits that would be quite slow.

You could look at an FPGA "Field-Programmable Gate Array". Which are board designed to be programmed by the customer for a specific task. This does require quite a good grasp on programming and still I don't know if it would out perform an ASIC or GPU.

FPGAs will not outperform and ASIC, but they may outperform a GPU.  ASICs have a much higher price/performance ratio compared to both FPGAs and GPUs.  Also, I want to make a note for our question-asker here that making your own ASICs would cost lots of money, usually millions.  That's why it's usually best just to order them from someone who sells mining ASICs, but all the models that will be making significant money would still cost a few grand.  Also, beware of scams, especially if a website only accepts wire-transfers for payment.

Edit: Fixed my grammar.