I was in my workshop when my daughter yelled at me that there was someone at the front door for me. The visitor was quite an elegant looking woman in her early forties at a guess. I asked what she wanted and she answered, "Darren tells me that you can manufacture parts, one offs." I told her that I could make lots of things when she produced some plans. I took her through to the workshop and spread the plans. There was nine parts that looked as if most went together. I couldn't tell what the overall project was for, but whatever it was, it was fairly large. From the drawings I could see that there was nothing that I couldn't make. I told her that I could make the parts and asked what they were for. All she would say was it was an experimental project and was a secret. We agreed a price and I told her it would take about a week. She seemed pleased, and I saw her out after she handed me her business card. The parts needed milling, turning and welding. I worked out the best order to do them in to save tripping over lots of tools. That's the problem with a small workshop. I cracked on with it and was finished in the time agreed and the day after Valeria returned for her parts. I had tried putting them together, but still couldn't tell what it was meant to do. She paid me and I put the parts into the boot of her car. The following day she phoned me and said that the parts didn't fit. I told her to bring them back and I would check them. She was back within an hour and I took the parts into the workshop and she showed me the bits that didn't fit. Out came the Vernier Calipers and tape measures. I measured the parts in front of her and showed her the measurements compared to the plans. I had made them to the exact measurements on the plans. She agreed that they were right. She asked could I modify them and I had to tell her not without all the other parts as one change here could affect two fittings there. She agreed that she understood. Then she gave a big sigh and agreed to bring the rest of it around the following morning. As agreed she arrived with the rest of it. I could now see what it was. It was like the children's horse that they sit on and as they push and relax with their feet the horse moves forward. The only difference was this one was adult sized. She left all the parts and left. She looked just a little flushed as she dashed off. It took most of the day to modify the parts. My fifteen year old daughter see it and said she wanted a go. I explained that it wasn't completed yet and I was still trying to work out where a few of the bits went. Next morning I started to assemble the bits and it was going together well , but I could see was that there were several bits that didn't make a lot of sense. I tried the bits various ways and decided there was only one way and fitted them and when I dropped the horse over the workings it became obvious what it was. It was a sex toy. As the toy moved along a rubber dildo would raise and lower, basically fucking the rider as she rode and moved the horse along. I was glad my daughter was out for the day. I tried it the best I could without riding it, I had no wish for the ten inch cock to be probing my arse. It all seemed to work. I rang Valeria and told her it was complete but needed testing. She said she would be right over. She was at the door in under ten minutes. She looked at it and moved it along and watched the cock raise and lower. Then she hiked up her Midi length skirt and straddled the horse. She wasn't wearing any panties and just impaled herself on the cock. She placed her feet and pushed. The horse raised itself and she went, "Ooooh," and as she stopped pressing the horse dropped and she want "Aaaah." the horse moved along the workshop floor about a foot. I couldn't see it, but the cock must have raised and lowered in her pussy. She pressed and released about ten times. the horse had now moved about ten feet and was close to the end of the workshop. She Oooh'd and Aaaah'd on each movement. She put her feet down on the floor and turned the horse around to face the other way. She now had about twenty five feet of free space. She didn't need it as she made about twenty feet and almost collapsed. She was hugging the horses head and shaking. The dirty cow had come on the horse right there in front of me. I realized that watching her and knowing what was happening under her skirt had given me a rock hard cock. I helped her up and off the cock and the horse. She was hanging onto the horse with one hand on it's head and the other on the cock that was glistening from her juices. She was still breathing very hard. I took the liberty of slipping my hand under her skirt and stroking her exceedingly wet pussy. Valeria just moaned. She made no attempt to move away or push me away and not even tell me no. I could feel her arse pushing back onto my fingers that were now deep in her pussy. She was moaning and groaning as I fingered her. "Fuck me, please fuck me," she asked. I raised her skirt and took my cock out of my trousers. I soon married our parts together. She was moving her hips as if she was riding the horse. Her pussy was trying to milk my cock. The feelings were fantastic. It must have been just as good for Valeria as she came for the second time, but on my cock this time. Her pussy tightening caused me to come and I pumped my full load deep in her pussy. It was a while, she had recovered and I had zipped my cock away. She still looked rather flushed. I wrapped the horse in some old sacks to take it out to her car and fit it into her boot. It was a good job that she had a big estate car or it wouldn't have fitted. She offered that she would make the payment for modifications if I went to her house to install it that evening. It didn't need any installing, but I agreed to go anyway. I arrived and carried it into the house and down to the cellar. I was amazed at the various toys she already had. She stripped her blouse and skirt off. Valeria was almost naked if not for shoes and jewelry. She was quick in getting on the horse and riding it around the cellar. It took two times around the room before she came again. I had her off the horse and taking my cock again as I laid her across a table. After she calmed down she demonstrated most of the other toys. I fucked her again on a rather special swing seat. Before I left, Valeria asked if I would be up for making other toys for her. I told her that I would, and to call me when she knows what she wants. Back home my daughter asked could she have a go on the horse. I told her that It had already gone to it's owner, to soften the blow I told her it didn't work very well. Well I could hardly tell her that it had fucked Valeria to orgasm twice already that day, could I. It wasn't that long before I got a call from Valeria saying he had another toy that she needed making.