This Instructable shows you how to make a set of four plant presses (also called "botanical presses" or "flower presses").

Each press can accommodate at least ten pressed specimens (or "pressimens"), which should be enough for any classroom.

The supplies for this project will cost about $15 (or $20 if you opt for fancy decorations).

Since they're made of easy-to-cut MDF (medium-density fiberboard), the plant presses can be built by middle-school-aged students using only hand tools.

Let's get started!

Step 1: Materials and Tools

Here's what you'll need.

Materials for the plant presses:

A 24" x 48" sheet of 1/4"-thick MDF (medium-density fiberboard)
(16) 3" long, 1/4" bolts
(48) 1/4" washers
(16) 1/4" lock washers
(16) 1/4" nuts (the regular, hexagonal sort)
(16) 1/4" wing nuts
Scrap cardboard (lots of it, see step 6)

Tools:

Hand saw (Not pictured. If you don't have one, there's a way around using one -- see the next step.)
Manual drill
1/4" drill bit
Cylindrical "rat tail" file, or additional drill bits (see step 5)
Sandpaper
Some kind of clamp
Ruler
Pencil
Pliers or a wrench (see step 4)
Scissors

Optional decoration supplies:

Four picture frames (I got mine at the dollar store)
Adhesive Velcro squares
Paint

Step 2: Cut the Boards

Cut the MDF sheet into eight squares that are 12" on each side, as in the cartoon above.

A few extra notes:

MDF is easily cut with a hand saw, and also very easy to drill through -- that's why we're using it in this project. It's somewhere between cardboard and plywood on the "difficulty of cutting" scale.
If you don't have a saw, hardware stores will usually cut up sheet materials for you (for a small fee). Hand the fine folks at the hardware store the diagram above, explain that it's for a school project, and give them your most winsome smile.
For our international friends: I've specified lengths in inches in this project, since it's based on inexpensive materials that are commonly available in the United States. It's not necessary for you to use the exact dimensions mentioned in this Instructable -- use whatever materials are available near you. If you're curious, however, here are the equivalent measurements in centimeters. (If you have any advice on adapting this project for metric-system-using countries, please leave a comment!)
- 1/4" thick = 0.635 cm (I bet 6mm wood would do the same job.)
- 24" wide = 61 cm
- 48" long = 122 cm (I've read that 6mm x 610mm x 1220mm MDF is available in Foreign Climes)
- 12"-wide-square = 30.5 cm
- 1/4"-wide-bolts are pretty similar to M6 bolts

Step 3: Drill the Holes

We're going to drill a hole in each of the four corners of the eight squares we just made.

Measure and mark a spot in the corner of each square; it should be 1/2" (~13mm) from each edge. [See photo above.]
Stack two squares together, clamp them to the edge of a table, and carefully drill a 1/4" (~ 6mm) hole through both squares. (Drilling through two squares at once helps ensure that the bolts and holes will line up properly when you assemble your plant press. Plus, it means you'll only have to use the drill 16 times instead of 32 times.)
Repeat for each of the corners of your square, then for all four squares.

Three tips:

It's easy (and safe) to clamp the squares so that one corner at a time hangs over the edge of a table. After drilling each hole, rotate the square so that a new corner hangs over the edge, re-clamp the boards, and drill the next hole.
To help keep the holes in the squares aligned, you can insert a bolt into each each hole after you drill it.
Keep each pair of squares together as you work; it'll help you remember which pair belongs together when assembling your presses.

Drilling Holes 1.tif
Download

Step 4: Attach the Bolts to the Bottom Square

For each of the four presses, pick one square from each pair to be the bottom, and one square to be the top.

Each of the four holes will need a bolt, three washers, a lock washer, a nut, and a wingnut.

Here's how to attach all of that hardware to each of the holes in the bottom square:

Slide a washer onto a bolt.
Insert the bolt (with a washer) through the hole in the board.
Slide a second washer onto the bolt, so that the board is sandwiched between two washers.
Slide a lock washer onto the bolt. (As its name implies, this will help keep everything locked in place.)
Thread a hexagonal nut onto the bolt.

Repeat that sequence for each of the four holes in the bottom board. You should end up with something like the picture above.

To tighten the nuts onto the bolts, you'll need one tool to hold the bolt's head, and one tool to hold the nut. You can use any two of the tools shown in the introduction, or find a more-creative way to tighten things down. (I used a pair of pliers and a wrench, as shown in the photo above.)

Step 5: Widen the Holes in the Top Square

Odds are, no matter how carefully you drilled the holes, the holes in the top square STILL won't line up perfectly with the bolts in the bottom square. We'll widen the holes in the top square to make it easier to fit the press together.

If you have a cylindrical "rat tail" file, you can use it to widen the holes as shown.

If you don't have a suitable file but you DO have a collection of drill bits, you can widen the holes by drilling through them again with a slightly wider bit. (What's slightly wider than 1/4"? It makes for a fun lesson in fractions, right? Right?)

Step 6: Cut Up Some Cardboard

When you get to pressing your plants, it helps to sandwich them between layers of corrugated cardboard.

If you've got access to a Dumpster, a ruler, and pair of scissors, you're all set to make yourself some botanical specimen spacers!

If you've built your presses to the dimensions suggested here, then 10-1/4" by 12" rectangles (~ 26cm x 30.5cm) are a good fit.

(One of the reasons I made the plant presses to these dimensions is so that they can be used with the 9" x 12" pads of watercolor paper that are widely available. They're also a perfect match for the typical "Extremely Local News"-sized newspaper.)

Each plant press can hold 10-12 sheets of cardboard; you'll need at least one cardboard rectangle per student specimen, so it helps to make a lot.

Step 7: Put Your Press Together!

You're ready to put your presses together!

Here's the stacking order, from bottom-to-top:

Bottom square
A cardboard rectangle
Some absorbent paper (school-newspaper-sized newsprint works well)
Your botanical specimen!
Another cardboard rectangle
More absorbent paper
Another specimen!
Another cardboard rectangle
Yadda, yadda, yadda...
Top square
Four washers (one on each bolt)
Four wing nuts (one on each bolt)

Then, tighten down the wing nuts, and leave your specimen to dry!

It's a good idea to give your specimens about a week to dry fully. However, you can speed up the drying time by:

Putting your presses next to a fan, heating vent, or other source of ventilation
Leaving your plant presses in a car that's been parked in the sunshine with the windows rolled up

Step 8: Optional: Add Some Classy Decoration

Once you've amassed your first set of pressimens, you can use the presses themselves to show them off!

Place your favorite specimen on a piece of thick, acid-free paper and place it in a picture frame. (Watercolor paper works very well, and the 9" x 12" tablets are a good match to these plant presses.)

Use four squares of adhesive-backed Velcro to attach the picture frame with your specimen to the top of the plant press.

(If you'd like, you can paint both the press and the frame to match, or get more creative!)

If you're not going to place your pressed specimen in a frame, then you can paste it to a sheet of paper using school glue (such as Elmer's). Be sure to paste your identification and collection label to the sheet as well -- you're on your way to establishing your own herbarium!