Sure, start one. At this point, though, it might be more interesting to ask who doesn’t have one and why?
Not unless you have a LOT of free time on your hands. There are some good 3D printer firmware options available today. Re-inventing the wheel just for the sake of getting it in a different language (that isn’t realtime…) is a project for students. I’d rather work on things that don’t already exist or have lots of room for improvement.
Not to mention the fact that you probably couldn’t get step rates high enough to make a reasonably fast printer without RLP, even with a high clockspeed NETMF device. You could probably use dSPIN or similar SPI/I2C stepper drivers instead of A4988 or DRV8825 drivers, but now you’ve left the well-trodden territory, and you lose access to super-cheap hardware purchasable on eBay or similar sources.
Llilum may change things, but for now, you’re better off running Marlin on Arduino with RAMPS if you want to print with your printer. If you’re more interested in designing control software than you are in actually printing things, then this advice may not apply 
There are are few cheap i2c stepper drivers on eBay 
Arduino became too slow for my printer since I switched to smaller gears, 0.9° steppers and sixteenth microsteps driver configuration. So had to switch to 32bit closed source controller. Still super-cheap.
There are a few open source boards based on the Arduino Due 32 bit ARM cortex board. I used to use a RepRapPro that had a duet board. Duet - RepRap This could run 1/16 microstepping even with .9 degree steppers and run a webserver at the same time. There are probably other boards too now.
Personally i have a Wanhao i3 that is really good (after a bit of TLC). The new v2.1 and i3plus look even better though.
I’m running my printers on Duet boards (running RepRapFirmware) which are based on the Due architecture. It has the web frontend which alone is worth the upgrade. I’m building a new delta printer now that will have 0.9 degree steppers and 1/16 microstepping. No way a NETMF controller board could keep up. If that wasn’t enough, RepRapFirmware is just so much nicer to configure than Marlin or Repetier. I can change all configurations on the fly through the web interface w/o having to re-compile anything.
http://www.filastruder.com/collections/electronics/products/duet-controller-v0-8-5
@ ianlee74 - Yeah but that price though 
I definitely believe that the future of these things is in 32-bit MCUs. The AVR is past its prime here, and we need to move on. That said, the printer I built here next to me is running on Arduino+RAMPS 1.4, because price. I got the Arduino (clone), RAMPS, drivers (5x DRV8825), endstops (6x), RepRapDiscount smart controller (clone), and PCB heat bed (mk2b) for $50 delivered. They even threw in 5 of the useless little heatsinks to put on the DRV8825 that do essentially nothing.
Oh yeah, by the way, I finished my printer and it works pretty dang good, especially considering I’m in it under $350 including the first roll of Hatchbox PLA.
@ ianlee74 -
The board I’m running is based on 32-bit ARM chipset (STM32F103ZET6), but not open source. Configuration as easy as on Due but I paid for it $108 total (including WiFi option and 3.5" color touch screen display).
I just finish building my second delta printer a month ago. It’s a full size delta with heated bed and magnetic arms, all metal construction.
So currently I have 2 deltas. one with 250mm glass bed with PCB heater running Marlin on MKS-BASE V1.4 (RAMPS 1.4 compatible one piece board) and second 304mm aluminum bed with kapton heater running on closed source 32-bit chipset. Both printers are all metal frame construction and both with magnetic arms.
@ godefroi -
I used up about 20 spools of PLA and Hatchbox is my favorite.
@ EvoMotors - Hey Evo, what type of stuff are you printing? I don’t have one of these great devices, but I am thinking about it.
@ godefroi - unless there are pictures it doesn’t exist :whistle:
Here is the picture of the smaller one, and on the background you can see Garry telling @ godefroi “unless there are pictures it doesn’t exist”.
@ Gary - Here you go.
Also, printing a ~50mm bridge:
[quote=“EvoMotors”]
The board I’m running is based on 32-bit ARM chipset (STM32F103ZET6), but not open source. Configuration as easy as on Due but I paid for it $108 total (including WiFi option and 3.5" color touch screen display).[/quote]
For the same reason I’ll pay a little bit of a premium for GHI hardware (premium components and superior support), I’ll also pay a little bit of a premium for the Duet. I’ve got a direct line to David Crocker (the engineer/designer) and if there’s an question or issue he’s always Johnny-on-the-spot to provide a solution. I’ve tried the Chinese clones and after I started finding parts desoldering themselves and laying on the table mid-print, I decided it wasn’t worth the savings. In fact, I’ve gone through this process several times and now I don’t bother with anything except the best when it comes to the controller, the hotend, and the extruder. I’ve wasted too many hours fighting to get a print because of sub-par components.
Awesome! I’ve got a standard size (180mm dia) Mini Kossel I built almost 3 years ago and I’m currently building a new all-metal 300mm diameter delta. I picked up my CNC cut aluminum parts tonight. Current progress is attached. Sorry for the mess… My build log with full details is here.
Well, it would seem we started that 3D printer thread. 
@ godefroi - Nice! Is that a CoreXY? If I build another one, its going to be a large CoreXY. Building a CNC is next in the queue, though.
@ Terrence Get one. You won’t regret it.
@ EvoMotors Do you have a link to that STM32 board?
@ ianlee74 Very interesting build log. I like the decision to go with the mains voltage heated bed. More printers should do this IMO.
@ godefroi That looks like it’s printing really well. What’s the build volume?
What materials do people print with most? I am big on ABS. I have my printer in an enclosure that seems to have eliminated warping and cracking. Once that’s sorted ABS prints like a dream. PLA is just too brittle and low temp for me.
[quote=“ianlee74”]
The 32-bit board I’m running is Chinese, but not a clone of another board. Its just reasonably priced and it does have good a customer support. I mean the real customer support.
@ ianlee74 - Yes, it’s the Fuse Box design: FuseBox CoreXY 3D Printer by _AlexY - Thingiverse and FuseBox ~$300 CoreXY Printer
It’s a very inexpensive design that works surprisingly well. It has all the downsides of some of these designs, though, mostly related to the cantilevered bed. It’s a “standard” roughly 200mm by 200mm by 200mm build volume. The other weakness in the design, I believe, is related to print cooling. Still, it printed the 50mm bridge like a champ. I haven’t tried the 100mm bridge yet.
These things are super fast, though. I’ve printed at over 100mm/s without major defects.
You just need to add part cooling fan. There few designs of it for your printer model available on http://www.thingiverse.com/
@ ianlee74 -
You can safely use much larger bed diameter with these alms length on your printer.
Bed on my delta extends way over the lower body and I can still accurately utilize 100% of it. So I don’t understand why most people using such small bed diameter on large deltas. The bed diameter smaller than printer base only make sense if you planning to enclose your printer in acrylic tube.
I feel under powered w/ my malfunctioning Solidoodle 3.
I did one final iteration of the case which is now in four parts.