Enlarge (Practically) Anything Proportionately - Overview on a Giant Pen




Introduction: Enlarge (Practically) Anything Proportionately - Overview on a Giant Pen

This is the best way I know to reduce or enlarge an item or sculpture. Keep in mind this is old school so no computers were harmed in this process. To give you an idea of how it works I took pics of this display as I went along.
Take any item in this case a 6" high pen (orange in the photo) and enlarge it to 84" (blue in the photo). 
All of the measurements I used were taken off the orange pen and factored up. Yes...it's a little tedious but it ends up being very accurate. 

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Taking Dimensions and Factoring Up

In this case I divided the finished size I wanted (84") by the original pen size (6") equals 14.  Using this factor of 14,  I multiplied any dimension I took off of the original pen. Because the pen is very small I used vernier caliper and got as many detailed measurements as I could stand. 
 Whatever you choose to enlarge all you need to know is the finished size you want, and be able to take dimensions from the original. Do the opposite to reduce something and always use the same unit of measurement when going from original to finished size. 

Step 2: Construct Parts

With the new dimensions I started to make parts of the pen. I used SignFoam3 (15lb density by 2" thick) and glued layers together with polyurethane glue (Gorilla Glue) to get the sizes I needed. This material is great for carving and machining, it also takes solvent based paints and resins without melting. Most of the pen was done on the wood lathe.

Step 3: Prime and Sand

I primed and sanded the parts using a heavy bodied primer and 220 sand paper. Since the pen I was building had a translucent  shell, I needed to get pieces vacuum formed. I started by laminating a sheet of craft paper down the middle of each block of sign foam. Once I turned each piece on the wood lathe I was able to hammer a chisel along the craft paper and split the parts in half. Next I added a 1" block to the bottom of each half. That makes an allowance for trimming of excess material on the vacformed parts. 

Step 4: Prep Vac-formed Parts

My neighborhood plastics shop have the vacform equipment and ovens to do pulls of this size. They to drill tiny holes in the plugs to suck the heated plastic into detailed areas. In this picture I have pulled off the 1" spacer and used a sanding disk to grind off the excess flange and make the plastic flush to the plug. Use a sanding block  for the final sand to make it perfect, a good tip is to spray paint the top of the plug so you can see when the sander gets too close. I also got more than one pull done just encase I screwed up.

Step 5: Glue Parts

My next step was to butt glue the halves together. The plastic we used was 1/8" polycarbonate, strong but once it's stretched in the vacuum forming process it can be pretty tricky to bond. I use Weld-on #4 glue, it runs like water and actually melts the plastic together. Use a syringe and fine needle, the one in the picture is good but it will drip when you don't want it to.  If you get runs or drips don't wipe it off let it dry, it's less noticeable.  

Step 6: Paint Shells

When the halves are glued they can be painted. A translucent blue automotive paint was used. It was painted with thin overlapping coats, since it is see through the coats had to be as even as possible. Normally a plastic addhesion spray would be fogged on bare plexi but this time there was enough solvent in the light coats to bite into the poly. 

Step 7: Make Core Parts

I glued the halves together and turned them down on the lathe to make the innards of the pen. I then covered them with white and black vinyl.  

Step 8: Accessories

The pen accessories have been carved from SignFoam3. The heavy  bodied automotive primer soaks into the foam when it's sprayed on and makes the parts fairly durable. I used a spray bomb of black truck bedliner to get the right texture. 

Step 9: Base Construction

I made a base of plywood and topped it off with 3/4"MDF. The sides were covered with 3/8" thick snakeply (wiggle wood, flexply, it has many names) wrap that was stapled to the plywood ribs. I filled the cracks and staple marks with spot putty and used a router to radius the top edge. The hole on top is for a 2" stainless steel post that will hold the pen vertical. 

Step 10: Start Assembly

Once the base was done and the s.s. tube in place , I used an ABS pipe as a sleeve and mount for the pen parts. Starting with the bottom knob I glued it to the ABS and secured a block in the top of the pipe to keep the pen 4" above the base. 

Step 11: Apply Vinyl

I slid the inner core over the ABS pipe and glued it in place with the urethane glue. (Lightly spray non-porus surfaces with water the glue uses moisture to cure and foams up as it dries, great for filling in gaps and it sands off pretty good) Remember to measure and multiply every part, the springs in the pen ended up scaling to 5/8" dia. I used PVC flexible tube (Home Depot) and spray painted it silver. The vinyl numbers were applied and positioned by doing a test fit of the shell. 

Step 12: Assemble Shell

I screwed on the button from the inside of the shell. I also adjusted the fit of the shell to the knob and did a last check on the vinyl layout. 

Step 13: Top It Off

The clear reservoir is an unpainted section of the vacuumed formed polycarbonate. The red piece in the top is again SignFoam3 primed and painted red. Most of the time the pen will be displayed with the cap on but the reservoir can still be seen through the translucent blue.
The last thing put on was the cap and secured it with tiny screws (see intro pic). I breezed over the construction methods to keep the instructions to a minimum, if someone wants more detail on any part of it let me know. 

Epilog Challenge V

Participated in the
Epilog Challenge V

Be the First to Share


    • Toys and Games Challenge

      Toys and Games Challenge
    • Backyard Contest

      Backyard Contest
    • Silly Hats Speed Challenge

      Silly Hats Speed Challenge

    7 Discussions


    5 years ago

    do you habe an email or number i can contact you at i am interested in getting something made


    6 years ago on Introduction

    Glad to see my vac-formed parts are on this site... great job on the finished product looks really good on the stand


    Reply 6 years ago on Introduction

    Thanks...you did a good job on the pulls.


    Reply 6 years ago on Introduction

    I hear ya.....It was a prop for a trade show booth.

    Cool - and you even make it sound so easy. Well, I guess with a workshop like that at your disposal, it probably is.

    How much did this piece cost you, if I may ask, material- and work-wise?


    Reply 6 years ago on Introduction

    The best part about the shop is making a mess and not having to clean it up at the end of the day. Minimal tools for this mostly a Canadian Tire wood lathe, hand router and paint.