Rob explains: I start by making cuts around the sprue at the same level. I always start on the corner edges. Then I move down the sprue and do it again. I then go back up to the first level and cut the leaves deeper to overlap the lower row. When I'm happy with it I twisted off the center stub. The final step is to cut it from the sprue, making sure that the flat side of the clippers is towards the plant.The following pictures illustrate Rob's method:

The thing to understand (as illustrated by the pictures below) is that the greater the angle of the knife, the deeper the cut and the thicker the "leaf". The closer the blade is to lying flat against the sprue, the thinner and curlier the "leaf" will be.

1. (Fig. 1-1)First find yourself a piece of sprue and remove all the sticking out bits (clippers will be fine for this as it'll be tidied up later).Then, cut it to length. I use a Number 10 blade in my scalpel and this allows me to use a rocking motion to cut the sprue, little by little, into two (Don't try to go all the way through in one go as you'll likely end up snapping your blade and/or cutting yourself).Clean up any rough edges from where you removed the bits earlier, before continuing.

2. (Fig. 1-2)This is probably the most difficult step (yep, it's downhill from here).Using the same technique that you used to cut the sprue to length, cut the sprue in half, lengthways (the shorter the plank/sprue the easier this step is).

There's two ways this can be done and will give you the results shown in the diagram in Fig. 2. I'm cutting along the green line as this leads to a variety of sizes of wooden planks. The red line will give you all identical pieces with non-parallel faces, this will however allow you to make an overlapped look to the final wall/fence but will not be covered in this tutorial.

You have to be careful to get the cut as straight as you can, but a little unevenness can be solved afterwards with your scalpel and/or gives a bit of variation to your wood (and also can result in some nice broken planks if that is what you desire).

3. (Fig. 1-3)You pieces will likely end up bent after step 2 but can just be straightened by hand and any rough patches can now be fixed by removal or gluing with polystyrene cement.

4. (Fig. 2-4)The "wood" texture is built up by successive scratches with the side of the point of your scalpel (this gives thicker lines than using the cutting edge of the tip).Starting at one end, make many small scratches of roughly the same length and try to cover the whole width of the sprue, the more lines the better the result. Do not press too hard as successive passes in later steps will deepen some of the grooves.

5. (Fig. 2-5)Moving further up the sprue, keep making small scratches of even depth to the same length, makingsure that you fit in as many lines as possible.However, continue your scratches to the bottom end of the sprue and allow the scalpel to follow whatever path it likes. This will deepen certain grooves that were there from the previous step and eventually the scalpel will only fall into those grooves and will therefore leave some of the grooves as smaller scratches.

I have found that occasionally switching the scalpel round so that I'm scratching with the other side of the tip will aid the randomness of the resulting pattern as the blade will tend to follow different paths depending on which way it is facing.

6. (Fig. 2-6)Continue this way along the sprue.Once the grooves are deep enough at the lower end of the sprue you do not need to keep going over them and you therefore work your way up the sprue, all the time keeping the leading end of your scratches as evenly spaced as possible and allowing repeated passes to deepen grooves at random.

7. (Fig. 3-7)Keep this going until you reach about half way up the sprue, then turn it around...

8. (Fig. 3-8)Using the same technique, start at the other end and work your way towards the middle.

9. (Fig. 3-9)Make sure to go over the middle, where the two halves meet, until the grooves are an equal depth and appear to continue the whole length of the piece.