This 8 legged crawler creeps around the lawn frightening trick or treaters with some unexpected side effects that leave the lawn the path least traveled and the candy bowl a place not many dare to adventure close to. The project is Robomower powered which puts the electric robotic mower to use during the off cutting season. For this project I used the Friendly Robotics RL-1000 but any model should work well, many older models can be purchased on ebay. The power pack consists of two sealed 12V, 17Ah batteries that will keep it crawling many hours into the night, lasting well past the last victim who will dare venture to your side of the street. It will stay within an area you set and will roam autonomously.
This instructable will show how to create this frightening hairy crawler that will keep even the oldest trick or treater from placing foot on the lawn.
1 square yard of black hairy fabric from fabric store.
1 or more plastic hollow baseballs
LED battery operated light pack
Red spray paint for plastic
8 Wire coat hangers or other stiff wire of similar gauge.
1/2 in. x 6 ft. Polyethylene Self-Seal Pipe Wrap Insulation, Dark gray
Insulating Foam Sealant
Hot glue gun
Rubber or cloth gloves
16 gauge wire, approx 50 to 100 feet
Robomower or other robotic lawn cutter
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Start by removing the mower battery first, then remove the mower blades for safety. Most blades clip on and on this model can be easily removed by squeezing two tabs and pulling the blade off the shaft. These mowers incorporate bumper sensors and other safety features that make them safe to leave unattended but I recommend removing the blades and, if the feature is available, stop the blade motors using the controller.
Using pliers open a wire coat hanger straighten the wire and insert it into the foam pipe insulation centering the wire along the pipe insulation so there is the same amount of wire at each end of the pipe. You can duct tape the wire inside of the pipe insulation but you will get better results from spraying an insulating foam such as Great Stuff into the cavity of the insulation covering approx an inch or two of the wire at each end of the pipe insulation, then seal the pipe insulation by removing its protective strip and by pressing the pipe insulation together to close the gap permanently. The wire coat hanger will help the legs hold their shape when we bend them to form legs later.
Take your fur material and drape it over the mower then complete a rough cut of material outlining the mower, leaving several inches of overhang to trim off later. Keep all leftover scraps for covering battery and controller compartments, minor repairs, and for hair on the legs. Using hot glue gun start attaching the fur to outer front edge and under the front edge of mower until entire front edge is glued on. The body shape of this mower works well for this application but if you need to add some shape to the body when using a different model mower you can glue foam to the underside of the material.
To make the eyes cut a plastic ball in half and paint the outside red unless you have a ball already colored red. Two eyes will work but you can add more. Hot glue them to the fur material onto the front.
To light the eyes; cut slits in the material behind the eyes to insert the LED lights from a battery operated light pack. You can find these packs at electronics stores or at department stores during Halloween and Christmas, they run on a few AA batteries and have a power switch mounted on front of the battery case. Any color LED light pack will work. Insert LED lights through slits and into hollow eyes. Lights should stay in place but some hot glue can be used to secure them. Mount LED battery pack onto front of mower with tape or place into front handle opening, switch facing out. You will be able to switch lights on/off through fur later.
Cut 8 openings into fur at top of body to insert legs. Insert legs grouped next to each other with an equal amount hanging over each edge. Use duct tape to fasten the group of legs down to the mowers upper casing at the top center. Images below have the fur pulled back to show legs taped to upper case.
Hot glue the remainder of material to the sides and back of mower casing, only a small amount of glue is needed to hold the material in place. Trim access material around the bottom edges. Cut openings to access batteries and controllers. Cover openings by placing leftover material inside them.
Start at the top of the spider body and bend the legs upward where they come out from the body. At approximately 1 foot from that point bend the legs downward until they just touch the ground. Cut some fur from unused pieces of material to use for hair on legs. Use spray glue and spray top edges of the legs then stick hair to legs.
The robotic mower that powers the spider is confined to an area by the same concept as an invisible dog fence barrier, you stake down a singe wire in the area you would like the mower to stay within. On short notice I used the dog barrier wire found in the local hardware store because it is the same gauge and is colored green to blend in, but the mower companies sell extra wire also. A battery operated signal controller box will send a signal down the wire that sets up an invisible barrier. Run the single wire from a central point to outline the area you wish the spider to roam within and stake the wire down every couple of feet or more using plastic tent stakes or metal lawn staples. Stake the wire down in the area and pattern you wish to have the spider contained to and bring the end of the wire back to the starting point, forming a loop, where the ends will be stripped and screwed into a connector that plugs into the signal controller box. Stake the ends close together where they run to the controller, this cancels the signal out and the mower ignores this section of wire instead of following it to the controller. Hide the signal controller under some leaves, or in my case I placed it in a wooden decorative wishing well. Press the power button on the signal controller and you are ready to move the spider onto the lawn within the signal area. If you already have a wire area setup for mowing this section of lawn you can use this but I like to contain the spider to a smaller area that is closer to the view of my victims so I lay out a smaller area, disconnect controller from the normal lawn cutting loop of wire and connect it to the line staked down for the spider.
The spider skin is easily removed because the tape and the hot glue releases with a light pull and not many glue points are necessary to hold the skin in place. The spider skin can be stored in a large plastic bag until next Halloween.
Place the spider on the lawn, switch on the lights for the eyes and press the start button to watch the terror begin ! I find that the battery pack lasts from the time the first to last trick or treaters arrive. A single battery pack when fully charged will run this gory creature for more than 3 hours and the battery can be changed if more run time is needed. The spider will roam the lawn all evening randomly creeping out from behind trees, bushes and other dark areas toward unsuspecting trick or treaters.