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Fisher Space Pen Refill | Ultralight Hack v2

Ultralight Fisher Space Pen

Make the ultimate UL all-weather ballpoint pen for taking notes along the trail with just a standard Fisher Space Pen refill (SPR4) and a short length of heat shrink tubing!

The Fisher Space Pen and the associated SPR4 refill earned the reputation throughout the world for being able to write on almost any surface, at any angle, through grease, and even under water – and as so many backpackers already use one it seems like the perfect choice for this quick little hack.

This project takes about 2 minutes and creates a highly durable pen that goes perfectly with a Rite In The Rain memo pad or small notebook. A standard Fisher Bullet Space Pen weighs 2oz (56g), the refill with shrink tubing weighs just 3g.

Ultralight Fisher Space Pen

I used 3/8″ heat shrink tubing that has a 2:1 shrink ratio (3/32″) and found that it formed tightly enough around the contours of the refill. You’ll even see in the photograph below that if you leave a small amount of the tubing overhanging the non-working end of the refill, it will shrink nicely to form an enclosed end.

Ultralight Fisher Space Pen

Be sure to check out my previous version of the Fisher Refill UL pen hack that does not require any heat shrink tubing, just a small piece of duct tape! For those of you growing tired of hearing about heat shrink tubing, I promise this will be the last blog post about it for a very long time =)

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  • What is the weight difference between the refill with the tubing and the refill in the standard pen casing?

  • James Conley

    As the old Russian joke goes – America invented the space pen that can write upside down, Russian used a pencil.

  • James, I know – I happen to like pencils myself. They work great :)

  • Hold on.. I just happen to have one handy. The standard Fisher (Bullet) Space Pen in stainless steel, including the refill weighs 57g (2oz).

  • Guest

    Interesting space pen trivia – both the Americans and the Russians initially used pencils.  The problem was that the pencil shavings would clog the air filters.  Mr. Fisher developed the space pen privately (no NASA funding) and offered up for sale.  The first NASA use and the first Russian use happened within a few months of each other.  All of that said, the space pen “stowaway” is a good compromise between the full-size Bullet and a bare refill (no cap).

  • Dude, that is awesome! Is there any end as to what you can use Heat Shrink for?!

  • Paula

    If the full space pen weights 2 oz, what does the shrink tubing pen weigh?   Great hack!  Definitely going to make myself one. 

  • Probably not, but I think I need to stop with the heat shrink tubing posts before I drive everyone crazy. That doesn’t mean you can post some and I’ll link to ya…(wink)!

  • It’s official – I’m about to have my UL license revoked for forgetting to include the weight in the actual blog post, OMG.  Sorry Paula, thanks for asking me though. The weight of the refill and shrink tubing is a measly 3g!

  • Ryan Schwiebert

    Your addiction to heat shrink is getting pretty serious Brian…

  • I know! I’ve had to put it all away and out of sight so I won’t keep playing with it. It should have some sort of health warning on it :)

  • That’s great trivia and I’ll admit to being a huge space race geek. The Stowaway is a good compromise but still doesn’t quite fulfill the need that I had – besides, what fun would it be if you could just go out and buy a piece of gear without the need to hack it?

  • Zandhaas

    Why all this trouble when you could buy the Fisher Stowaway? Super lightweight, and with a clip as bonus.

  • I like the hack.  Using shrink tubing for this is very smart thinking.  I would imagine that it makes the pen easier to hold and you get less slippage too. 

  • Well the reason why I choose to do this instead of just buying the Stowaway version is because I’ve tried the Stowaway pen and didn’t much care for it. Unlike the excellent (but heavy) bullet pen, the Stowaway is cheaply made and nearly every one that I’ve had ends up with the lid becoming permanently loose after a few days of use. My personal preference of course, but if you like the Stowaway and haven’t had the same issues that I and a lot of others have had, then that’s cool.

  • You’re absolutely right. Even in the cold rain this thing is incredibly tactile and easy to keep hold of. Combined with my RITR memo pad I have a weather-proof writing solution!

  • Where did you get your heat shrink tubing and how do you shrink it (hair dryer ?).

  • Hi Shane, I got my first batch of heat shrink tubing as a Christmas stocking stuffer gift from my wife, I’m pretty sure she bought it at Walmart in the car electronics department.

    I’ve found that the cheapest place to buy it in small quantities is my local Home Depot store. They sell it in various colors and in different widths. I find 3/16″ to be about the most useful width to have.

    I’ve tried using my wife’s hairdryer, but it takes a very long time to reach the temperature necessary to initiate the shrinking (95 C, 203 F). If you have a paint stripper heat gun that would be perfect, but I use a Bic Mini lighter and carefully wave the heat shrink over the flame high enough so as not to burn it. Works really well.

  • That is one cool pen to have on the trail especially when I like to journal during hikes.

  • I have a space pen, bullet I think, I’m not that keen on it!!, when I take the lid off I have to wipe the gloop away from the nip and it gloops up sometimes when I’m writing with it!
    From all the good reviews I have read about them, maybe mine is faulty?!?

  • My experience with the SPace Pen refills is that they glob up all the time. They never ‘not’ work unless they are empty, but they do get messy.

  • JW

    Thanks for the post! I found it to be inspiring! Using the post above as a guide I was able to get a compact version of a sharpie liquid pencil, eraser and all.

  • Adam

    No, they didn.t They used the exact same Fisher pens that the Americans used. Pencil shavings around delicate instrumentation you’re depending on is a pretty dumb idea.

  • Adam, James said it as tongue in cheek. Whether it’s true or not there’s no need to take a bad tone here – ok.

  • neko69

    Well, I do…

    Why don’t You try with heat shrink tubing.
    Kind regards,

    • For a lid?

      • neko69

        I know it sound stupid and I am not to familiar how does it work exactly (heat shrinking tube), but I was thinking that You can apply smaller diametar tube as a lid and if You do heat it just enough to fit but not to “squeeze” it all the way….
        Probably wron idea…
        kind regards,

        • Oh I see what you mean. Use the same rubber heat shrink tubing, just don’t shrink it quite as tight. That’s not stupid, that’s pretty clever!

          • neko69

            Yes, that was what I was thinking. If You will try it pleae post the results.
            Kind regards,