Laser plotter

Hello, I plan to make a laser plotter (so like a CNC) out of an old pen plotter. I will take the standard bluray diode, PHR803T at 125 mA. But I am still not sure how I can cool it. The laser will have to run for longer times, so I think I need a big heatsink, the Aixiz could be too small. But such a plotter is made for these pens:

And how you can see they are not that big, so a plotter isn't meant to carry big weights around. Any tips for me?

Oh, I had not so much time when I wrote the first post, please excuse my double post (but I think if I edit no one will see it and it's important for me).
So, well, I am the new one here, yeah, I am newbie, but no, I don't wnat to brun stuf with teh lazr. I have read every single safety rule on the net about lasers (okay, nearly) and my eyes are important for me. I am able to do some handworking, have experience in drilling, cutting, screwing, and so on, things together, I can solder and built my first robot with 13 or so. But I do not have a lathe, If I hado ne (and ocould handle it ) the heatsink would not be a problem for me... So, what do you say? Please say anything at least, also, If I ask the wrong way. But please - I have searched, and I used the search function I just have the problem that I need a small, light-weight heatsink that can handle a lot of heat. Google translator means I should say I need a jack of all treats, who knows whether this is proper english or not... And thanks for all help, maybe still coming. I hope so.

A PHR won't need any extreme heatsinking(but it will need more than just an aixiz module) but heat dissipation is the least of your concerns. Using a PHR.. all you'll be cutting with that DIY laser cutter is thin black paper. If you switch to a 1W 445 diode, you might be able to move your cutable materials list up to thin cardboard and some types/colors of cloth.

Thank you. I already thought an Aixiz might be a bit less. I think I will get my plotter today or tomorrow and will let you know some measurements. And yeah I know maybe I can only cut black paper - but I do not want to handle a 1 W Laser at the beginning, also because it's expensive. Maybe later, we'll see. I take this step by step But which heatsink whould you say would be the best?

It doesn't take a whole lot of thermal mass for a PHR. People use them in pen hosts all the time for instance. Plus you could incorporate some relatively simple radial fins into the design by machining grooves into the heatsink and the plotter moving the laser around will aid in the cooling.

Since your just cutting with it, you can still get higher power relatively cheaply. 1W 808nm diodes are roughly $10 off ebay. Your going to need better heatsinking with that though. If you ever want higher powers though, you'd probably have to switch to some type of fiber coupling. And also upgrade your plotter bed as well. If it's plastic, the PHR will probably be leaving streaks in it as it is. 1W would be cutting groves in it after very much usage.