Karas Kustoms K Series Guide

Karas Kustoms K Series Guide

Karas Kustoms makes pens for the serious pen user. Machined in a small shop in Arizona, their rugged pens are designed to be “the last pen you’ll ever need.” Karas Kustoms controls everything from product development to production, which guarantees the quality and craftsmanship of their product.

Their first project was the Render K pen, which launched on Kickstarter back in 2011. Initially designed to house the popular Hi-Tec-C refill, the newest version of Render K now comes with a Pilot G2 refill and is compatible with dozens of refills. The success of Render K spawned Fountain K–a fountain pen that features interchangeable parts with Render K. In this article, we introduce the different variations of the K series pens and show you how to convert one to the other.

Render K

Render K

The ultimate EDC (everyday carry) pen, Render K is a sleek machined pen that takes your favorite gel or ballpoint pen refill to the next level. It’s a pen you’ll want to show off and use for a lifetime. Render K comes in three different metals: Brass, Copper, and Aluminum. The Brass and Copper are raw and can be polished to stay shiny. However, we love the character and patina that develops over time on these pens with age and use–it makes your pen truly unique.

Render K comes with a Pilot G-2 refill, spring, and spacer. Use the spacer with Parker-style refills. A complete list of compatible refills can be found here.

Fountain K

Fountain K

If fountain pens are are more your style, we recommend taking a look at Fountain K, Render K’s fountain pen brother. Machined from sturdy aluminum that’s built to last, it’s a weighty, no-fuss, no-frills pen stripped of all unnecessary bells and whistles. The aluminum Fountain K is available in eleven striking colors with a fine nib and silver grip. A Schmidt K5 converter and five black ink cartridges are also included.

Fountain K pens come fitted with Bock nibs. These stainless steel nibs are high quality and made in Germany.

Conversion Tools

The unique modular design of the K series pens allows you to convert a Render K to a Fountain K and vice versa. You can also customize your Render K and Fountain K by swapping grips and nibs depending on your mood. Note: the old version of Render K (marked as Last Chance) is not modular and cannot be customized or converted.

To change between pens you’ll need:

K Series Conversion Tool

The K Series Conversion Tool is a screw that allows you to remove the plug in a Render K in order for it to be used as a Fountain K. A plug with an O-Ring is also provided.

Render K Grip Sections

There are five available grip sections: Aluminum Black, Aluminum Silver, Tumbled Raw Aluminum, Brass, and Copper. Grip sections come with an O-ring and plug to help convert a Fountain K to a Render K. You may not need these parts if you are just swapping out grip sections to customize your Render K.

Fountain K Nib and Grip Sections

Fountain K features the same five grip sections as Render K: Aluminum Black, Aluminum Silver, Tumbled Raw Aluminum, Brass, and Copper. You can also choose from five different Bock nibs: Extra Fine, Fine, Medium, Broad, and 1.1 mm Stub Nib. Make sure you have both a grip and nib section to successfully convert from Render K to Fountain K.

Switching Nib Sizes on a Fountain K Pen

1. Clean the nib. Grip the nib firmly with your thumb on the feed of the nib.
2. Gently unscrew the nib section from the grip section by twisting the grip section counterclockwise and the nib section clockwise. Do not pull on the nib section as this will damage the internal threads of the nib section.
3. Insert the new nib section into the grip section.
4. Gently screw the nib section into the grip section. Now it’s now ready to use!

How to Convert a Render K to a Fountain K

1. Unscrew the grip section from the barrel of your Render K pen.
2. Stick the K Conversion Tool into the barrel of the pen. Twist it until it screws securely onto the internal threads on the plug.
3. Pull out the K Conversion Tool. The O-Ring and plug should come out with it.
4. Take the Fountain K grip and nib sections. Insert the nib section into the grip section carefully. See the previous section on how to do this.
5. Screw the grip section onto the barrel. Now you have a Fountain K pen!

How to Convert a Fountain K to a Render K

1. Unscrew the Fountain K grip section from the barrel.
2. Take the plug that came with your Render K grip section. Screw the plug onto the K Conversion Tool. Stick the plug firmly into the bottom of the pen body, O-Ring side first. Then unscrew the K Conversion Tool from the plug and remove it from the barrel.
3. Insert the refill with spring and spacer (if needed).
4. Screw the grip section onto the barrel. Your Render K is complete!


It’s hard to find a better “forever” pen than the Karas Kustoms K series. These rugged yet stylish machined metal pens are a tribute to American design and manufacturing. Have you tried a Render K or Fountain K yet? What is your favorite Karas Kustoms pen? Let us know in the comments below!

Product Line Material and Colors Refills Nib Sections Grip Sections
Render K Brass


Aluminum Silver
Click here N/A Aluminum Black
Aluminum Silver
Tumbled Raw Aluminum
Fountain K Olive Green










Tumbled Raw
N/A Extra Fine
1.1 mm Stub
Aluminum Black
Aluminum Silver
Tumbled Raw Aluminum